Conjugate vaccine using trimming function of erap1

ABSTRACT

wherein Xc and Yc are each a single bond or the like, and cancer antigen peptide C is an MHC class II-restricted cancer antigen peptide; or cancer antigen peptide D, wherein the cancer antigen peptide D is an MHC class I or II-restricted cancer antigen peptide containing one cysteine residue, or a salt thereof, for example.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of and claims the benefits of priority to U.S. application Ser. No. 14/780,241, filed Sep. 25, 2015, which is a national stage patent application of International patent application No. PCT/JP2014/059352, filed on Mar. 28, 2014, which is based on and claims the benefits of priority to Japanese Application No. 2013-074441, filed on Mar. 29, 2013 and Japanese Application No. 2013-158386, filed on Jul. 31, 2013. The entire contents of all of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present invention belongs to the field of cancer immunotherapy, and relates to a conjugate vaccine wherein cancer antigen peptide precursors are conjugated via a sulfur-sulfur covalent bond, which can be subjected to trimming by a particular peptidase and efficiently induces cytotoxic T cells.

BACKGROUND ART

For eradication of cancer cells in the body, cellular immunity, particularly cytotoxic T cells (cytotoxic T-lymphocytes, Cytotoxic T-cells, hereinafter to be referred to as CTLs) mainly play an important role. CTLs are produced by differentiation and proliferation of precursor T cells that have recognized a complex formed by an antigen peptide derived from a cancer antigen protein (cancer antigen peptide) and an MHC class I molecule, and attacks cancer cells. MHC in human is called human leukocyte-type antigen (HLA), and HLA subtypes such as HLA-A, B, Cw, F and G are known.

A cancer antigen peptide is produced through degradation (processing) of a cancer antigen protein synthesized in cancer cells, i.e., protein denaturation by reduction of a sulfur-sulfur covalent bond, degradation by proteosome or protease, cleavage into an optimum length by a trimming enzyme in the endoplasmic reticulum of the protein. The cancer antigen protein generally consists of 8-12 amino acid residues.

In cancer immunotherapy, activation of helper T cells is also important for activating other T cells including CTLs. In general, an antigen protein is degraded by intracellular lysosome, and a part of the peptide fragments, each of which is a peptide consisting of about 13-17 amino acid residues, binds as an antigen peptide to MHC class II molecule and is presented to helper T cell-TCR.CD3 complex to activate helper T cells. In human, HLA subtypes such as HLA-DR, DQ and DP are known.

As an antigen of a cancer vaccine, a cancer antigen protein itself or an antigen peptide derived from a cancer antigen protein is mainly used (see Non Patent Literature 1). Since a cancer vaccine using a protein generally contains various cancer antigen peptides, it can simultaneously induce a plurality of CTLs and helper T cells. However, the cancer protein vaccine possesses problems in stable supply and quality control. On the other hand, a cancer vaccine using a peptide can be conveniently produced or quality-controlled, but is mainly constituted by a single MHC class I-presented peptide antigen. Thus, it has been pointed out in recent years that efficient induction of CTLs requires further improvement (see Non Patent Literature 2).

One of the solutions for such problems is a multivalent antigen peptide-presenting peptide cancer vaccine. As such peptide cancer vaccines, a cocktail vaccine containing a mixture of a plurality of peptide antigens to be presented by MHC class I and class II, a long chain peptide vaccine containing peptide antigens to be presented by MHC class I and class II which are bound by an amide bond, and the like have been reported (see Non Patent Literature 2). In the case of a cocktail vaccine, however, since each peptide antigen composed of various amino acids shows various physical properties, the development of an optimal formulation capable of efficiently inducing CTLs corresponding thereto is often problematic. In the case of a long chain peptide vaccine, its production sometimes has problems similar to those of production of a protein. Furthermore, since the peptide antigens to be presented by class I and class II are bonded via a peptide spacer in a long chain peptide vaccine, it is difficult to control and predict the cleavage sites by intracellular enzyme. In the meantime, a peptide dimer wherein two peptide monomers are mutually bonded by a disulfide bond has been reported (see Patent Literature 1). Different from cocktail vaccine, a homodimer has two single peptides being bonded, and therefore, they have single physical property and can be produced conveniently. On the other hand, cancer antigen peptides are required to contain cysteine in their amino acid sequences, and therefore, applicable peptides are limited.

The process of presentation of a cancer antigen peptide on MHC class I involves a plurality of peptidases. Of such peptidases, Endoplasmic reticulum aminopeptidase 1 (hereinafter to be referred to as ERAP1) is one of the trimming enzymes in the endoplasmic reticulum (hereinafter to be referred to as ER), and has been reported to recognize a particular antigen peptide sequence and peptide length, and cleaves a cancer antigen peptide precursor from the N-terminal to control the length to be optimal for binding to MHC class I (see Non Patent Literature 3). However, there is no report to date on a conjugate vaccine using the trimming function of ERAP1. Moreover, although ERAP1 has been reported to convert a precursor peptide to a cancer antigen peptide by cleaving dicysteine from the N-terminal, it has been unclear whether the trimming is affected when an amino acid sequence containing cysteine is introduced to the N-terminal (see non-patent documents 3-6).

CITATION LIST Patent Literature

-   Patent Literature 1: WO 2004/063217

Non Patent Literature

-   Non Patent Literature 1: Nature Reviews Drug Discovery, 2009; 8;     685-686 -   Non Patent Literature 2: Cancer Journal, 2011; 17(5); 343-350 -   Non Patent Literature 3: Proceedings of the National Academy of     Sciences of United States of America, 2005; 102(47); 17107-17112 -   Non Patent Literature 4: PLoS One, 2008; 3(11); e3658; 1-12 -   Non Patent Literature 5: The Journal of Immunology, 2009; 183;     5526-5536 -   Non Patent Literature 6: The Journal of Immunology, 2010; 184;     4725-4732

SUMMARY OF INVENTION Technical Problem

The problem to be solved by the present invention is to provide a conjugate vaccine that induces CTLs efficiently.

Solution to Problem

The present inventors have conducted intensive studies in an attempt to solve the aforementioned problem, and conceived, when considering adopting conjugate vaccine, an idea of adding cysteine in a cancer antigen peptide, and further confirmed that the results of pharmacological tests using in vivo animal model or other tests strongly suggest that ERAP1 cleaves amino acids residues including cysteine extended from the N-terminal in diverse cancer antigen peptides generated by intracellular reductive cleavage of disulfide bond, and efficiently converts those peptides to cancer antigen peptides, which in turn led to the finding of preparation of a multivalent antigen peptide-presenting conjugate vaccine capable of inducing CTLs in the body, and the completion of the present invention.

To be specific, during the process of studying the solving means to the above-mentioned problem, the present inventors have obtained an idea of a method for introducing cysteine, which is necessary for forming a conjugate of two different cancer antigen peptides, into a desired position of the N-terminal or C-terminal, without influencing the antigen presentation by MHC class I. As a result of further study, the present inventors have created a peptide by introducing 0-5 amino acids containing cysteine into the N terminal of a cancer antigen peptide, and a conjugate of the peptides containing a disulfide bond via cysteine. Furthermore, the present inventors have confirmed for the first time that such peptides and conjugates are susceptible to trimming by ERAP1 in vitro and/or in vivo, which in turn results in the formation of a cancer antigen peptide, and thereby, completed the present invention.

It has been desired to develop a novel multivalent antigen peptide-presenting peptide cancer vaccine that can be produced easily, is applicable to various peptides, and induces CTLs with high efficiency. The conjugate invented by the present inventors has enabled the development of a multivalent antigen peptide-presenting peptide cancer vaccine that induces CTLs efficiently, has superior physicochemical properties, can be produced easily, facilitates production management, and is applicable to various peptides.

Accordingly, the present invention relates to the following.

1. A compound represented by formula (1):

or a pharmaceutically acceptable salt thereof, wherein X^(a) and Y^(a) are each independently a single bond or a divalent peptide group consisting of 1-4 amino acid residues, and a total of the amino acid residue number for X^(a) and the amino acid residue number for Y^(a) is an integer of 0-4, cancer antigen peptide A is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues, an amino group of an N-terminal amino acid of the cancer antigen peptide A binds to Y^(a) in the formula (1), and a carbonyl group of a C-terminal amino acid of the cancer antigen peptide A binds to a hydroxyl group in the formula (1), and R¹ is a hydrogen atom; a group represented by formula (2):

wherein X^(b) and Y^(b) are each independently a single bond or a divalent peptide group consisting of 1-4 amino acid residues, and a total of the amino acid residue number for X^(b) and the amino acid residue number for Y^(b) is an integer of 0-4, cancer antigen peptide B is different in sequence from the cancer antigen peptide A, and is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues or an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues, an amino group of an N-terminal amino acid of the cancer antigen peptide B binds to Y^(b) in the formula (2), and a carbonyl group of a C-terminal amino acid of the cancer antigen peptide B binds to a hydroxyl group in the formula (2), and a thioether group in the formula (2) binds to a thioether group in the formula (1); a group represented by formula (3):

wherein X^(c) and Y^(c) are each independently a single bond or a divalent peptide group consisting of 1-4 amino acid residues, and a total of the amino acid residue number for X^(c) and the amino acid residue number for Y^(c) is an integer of 0-4, cancer antigen peptide C is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues, a carbonyl group of a C-terminal amino acid of the cancer antigen peptide C binds to X^(c) in the formula (3), and an amino group of an N-terminal amino acid of the cancer antigen peptide C binds to a hydrogen atom in the formula (3), and a thioether group in the formula (3) binds to a thioether group in the formula (1); or cancer antigen peptide D, wherein the cancer antigen peptide D is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue or an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue, and a thioether group of the cysteine residue of the cancer antigen peptide D binds to a thioether group in the formula (1), provided when R¹ is a hydrogen atom, the sequence of the compound represented by the formula (1) is not identical to the partial sequence of a cancer antigen protein; 2. the compound according to 1, wherein X^(a) is a divalent peptide group consisting of 2 amino acid residues and Y^(a) is a single bond, or X^(a) and Y^(a) are each independently a divalent peptide group consisting of 1 amino acid residue, or X^(a) is a single bond and Y^(a) is a divalent peptide group consisting of 2 amino acid residues, or X^(a) is a divalent peptide group consisting of 1 amino acid residue and Y^(a) is a single bond, or X^(a) is a single bond and Y^(a) is a divalent peptide group consisting of 1 amino acid residue, or X^(a) and Y^(a) are each a single bond, or a pharmaceutically acceptable salt thereof; 3. the compound according to 1 or 2, wherein X^(a) is a single bond, and Y^(a) is a single bond, an alanine residue, a leucine residue or a methionine residue, or a pharmaceutically acceptable salt thereof; 4. the compound according to 1 or 2, wherein X^(a) is a single bond, an alanine residue, a glycine residue, a serine residue or a tyrosine residue, and Y^(a) is a single bond, or a pharmaceutically acceptable salt thereof; 5. the compound according to any one of 1-4, wherein X^(a) and Y^(a) are each a single bond, or a pharmaceutically acceptable salt thereof; 6. the compound according to any one of 1-5, wherein the cancer antigen peptide A consists of 7-15 amino acid residues and is an HLA-A, HLA-B or HLA-Cw-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 7. the compound according to any one of 1-6, wherein the cancer antigen peptide A consists of 7-15 amino acid residues and is an HLA-A1, HLA-A2, HLA-A3, HLA-A11, HLA-A24, HLA-A28, HLA-A29, HLA-A31, HLA-A33, HLA-A34, HLA-A68, HLA-B7, HLA-B13, HLA-B35, HLA-B37, HLA-B44, HLA-B45, HLA-B51, HLA-B52, HLA-B53, HLA-Cw2, HLA-Cw3, HLA-Cw6, HLA-Cw7, HLA-Cw8 or HLA-Cw16-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 8. the compound according to any one of 1-7, wherein the cancer antigen peptide A is an MHC class I cancer antigen peptide derived from a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A6, MAGE-A10, MAGE-A12, BAGE, DAM-6, DAM-10, GAGE-1, GAGE-2, GAGE-3, GAGE-4, GAGE-5, GAGE-6, GAGE-7B, GAGE-8, NA88-A, NY-ESO-1, NY-ESO-1a, MART-1/Melan-A, MC1R, Gp100, PSA, PSM, Tyrosinase, Proteinase 3, TRP-1, TRP-2, ART-4, CAMEL, CEA, Ep-CAM, Cyp-B, Her2/neu, VEGFR, hTERT, hTRT, iCE, MUC1, MUC2, PRAME, P15, RU1, RU2, SART-1, SART-2, SART-3, AFP, β-Catenin, Caspase-8, CDK-4, ELF2, GnT-V, G250, HSP70-2M, HST-2, KIAA0205, MUM-1, MUM-2, MUM-3, Myosin, RAGE, SART-2, TRP-2, 707-AP, Survivin, Livin and SYT-SSX, or a pharmaceutically acceptable salt thereof; 9. the compound according to any one of 1-8, wherein the cancer antigen peptide A is a peptide comprising an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 3) NYKHCFPEI, (SEQ ID NO: 11) EYLQLVFGI, (SEQ ID NO: 13) FLWGPRALV, (SEQ ID NO: 19) GLYDGMEHL, (SEQ ID NO: 26) SLLMWITQCFL, (SEQ ID NO: 27) QLSLLMWIT, (SEQ ID NO: 29) AAGIGILTV, (SEQ ID NO: 33) LIYRRRLMK, (SEQ ID NO: 40) YMDGTMSQV, (SEQ ID NO: 41) AFLPWHRLF, (SEQ ID NO: 43) VLQELNVTV, (SEQ ID NO: 50) YLSGANLNL, (SEQ ID NO: 53) KIFGSLAFL, (SEQ ID NO: 66) AYIDFEMKI, (SEQ ID NO: 83) AYACNTSTL, (SEQ ID NO: 84) KWFPSCQFLL and (SEQ ID NO: 85) GYDQIMPKK, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 3, 11, 13, 19, 26, 27, 29, 33, 40, 41, 43, 50, 53, 66, 83, 84 and 85 but containing alteration of amino acid residue(s), and having a CTL induction activity, or a pharmaceutically acceptable salt thereof; 10. the compound according to any one of 1-9, wherein the cancer antigen peptide A is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 19) GLYDGMEHL, (SEQ ID NO: 43) VLQELNVTV and (SEQ ID NO: 53) KIFGSLAFL, or a pharmaceutically acceptable salt thereof; 11. the compound according to any one of 1-10, wherein R¹ is a hydrogen atom, or a pharmaceutically acceptable salt thereof; 12. the compound according to any one of 1-3 and 6-11, wherein the compound represented by the formula (1) is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 89) CAGLYDGMEHL, (SEQ ID NO: 90) CLGLYDGMEHL, (SEQ ID NO: 91) CMGLYDGMEHL, (SEQ ID NO: 92) CAVLQELNVTV, (SEQ ID NO: 93) CLVLQELNVTV, (SEQ ID NO: 94) CMVLQELNVTV, (SEQ ID NO: 95) CAKIFGSLAFL, (SEQ ID NO: 96) CLKIFGSLAFL and (SEQ ID NO: 97) CMKIFGSLAFL, or a pharmaceutically acceptable salt thereof; 13. the compound according to any one of 1-11, wherein the compound represented by the formula (1) is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 98) CGLYDGMEHL, (SEQ ID NO: 99) CVLQELNVTV and (SEQ ID NO: 100) CKIFGSLAFL, or a pharmaceutically acceptable salt thereof; 14. the compound according to any one of 1-10, wherein R¹ is a group represented by the formula (2), or a pharmaceutically acceptable salt thereof; 15. the compound according to any one of 1-10 and 14, wherein X^(b) is a divalent peptide group consisting of 2 amino acid residues and Y^(b) is a single bond, or X^(b) and Y^(b) are each independently a divalent peptide group consisting of 1 amino acid residue, or X^(b) is a single bond and Y^(b) is a divalent peptide group consisting of 2 amino acid residues, or X^(b) is a divalent peptide group consisting of 1 amino acid residue and Y^(b) is a single bond, or X^(b) is a single bond and Y^(b) is a divalent peptide group consisting of 1 amino acid residue, or X^(b) and Y^(b) are each a single bond, or a pharmaceutically acceptable salt thereof; 16. the compound according to any one of 1-10 and 14-15, wherein X^(b) is a single bond, and Y^(b) is a single bond, an alanine residue, a leucine residue or a methionine residue, or a pharmaceutically acceptable salt thereof; 17. the compound according to any one of 1-10 and 14-15, wherein X^(b) is a single bond or a divalent peptide group consisting of 1 amino acid residue, and Y^(b) is a single bond, or a pharmaceutically acceptable salt thereof; 18. the compound according to any one of 1-10 and 14-17, wherein X^(b) and Y^(b) are each a single bond, or a pharmaceutically acceptable salt thereof; 19. the compound according to any one of 1-10 and 14-18, wherein the cancer antigen peptide B is an MHC class I-restricted cancer antigen peptide consisting of 7-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 20. the compound according to any one of 1-10 and 14-19, wherein the cancer antigen peptide B consists of 7-15 amino acid residues and is an HLA-A, HLA-B or HLA-Cw-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 21. the compound according to any one of 1-10 and 14-20, wherein the cancer antigen peptide B consists of 7-15 amino acid residues and is an HLA-A1, HLA-A2, HLA-A3, HLA-A11, HLA-A24, HLA-A28, HLA-A29, HLA-A31, HLA-A33, HLA-A34, HLA-A68, HLA-B7, HLA-B13, HLA-B35, HLA-B37, HLA-B44, HLA-B45, HLA-B51, HLA-B52, HLA-B53, HLA-Cw2, HLA-Cw3, HLA-Cw6, HLA-Cw7, HLA-Cw8 or HLA-Cw16-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 22. the compound according to any one of 1-10 and 14-21, wherein the cancer antigen peptide B is an MHC class I cancer antigen peptide derived from a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A6, MAGE-A10, MAGE-A12, BAGE, DAM-6, DAM-10, GAGE-1, GAGE-2, GAGE-3, GAGE-4, GAGE-5, GAGE-6, GAGE-7B, GAGE-8, NA88-A, NY-ESO-1, NY-ESO-1a, MART-1/Melan-A, MC1R, Gp100, PSA, PSM, Tyrosinase, Proteinase 3, TRP-1, TRP-2, ART-4, CAMEL, CEA, Ep-CAM, Cyp-B, Her2/neu, VEGFR, hTERT, hTRT, iCE, MUC1, MUC2, PRAME, P15, RU1, RU2, SART-1, SART-2, SART-3, AFP, β-Catenin, Caspase-8, CDK-4, ELF2, GnT-V, G250, HSP70-2M, HST-2, KIAA0205, MUM-1, MUM-2, MUM-3, Myosin, RAGE, SART-2, TRP-2, 707-AP, Survivin, Livin and SYT-SSX, or a pharmaceutically acceptable salt thereof; 23. the compound according to any one of 1-10 and 14-22, wherein the cancer antigen peptide B is a peptide comprising an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 3) NYKHCFPEI, (SEQ ID NO: 11) EYLQLVFGI, (SEQ ID NO: 13) FLWGPRALV, (SEQ ID NO: 19) GLYDGMEHL, (SEQ ID NO: 26) SLLMWITQCFL, (SEQ ID NO: 27) QLSLLMWIT, (SEQ ID NO: 29) AAGIGILTV, (SEQ ID NO: 33) LIYRRRLMK, (SEQ ID NO: 40) YMDGTMSQV, (SEQ ID NO: 41) AFLPWHRLF, (SEQ ID NO: 43) VLQELNVTV, (SEQ ID NO: 50) YLSGANLNL, (SEQ ID NO: 53) KIFGSLAFL, (SEQ ID NO: 66) AYIDFEMKI, (SEQ ID NO: 83) AYACNTSTL, (SEQ ID NO: 84) KWFPSCQFLL and (SEQ ID NO: 85) GYDQIMPKK, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 3, 11, 13, 19, 26, 27, 29, 33, 40, 41, 43, 50, 53, 66, 83, 84 and 85 but containing alteration of amino acid residue(s), and having a CTL induction activity, or a pharmaceutically acceptable salt thereof; 24. the compound according to any one of 1-10 and 14-23, wherein the cancer antigen peptide B is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 19) GLYDGMEHL, (SEQ ID NO: 43) VLQELNVTV and (SEQ ID NO: 53) KIFGSLAFL, or a pharmaceutically acceptable salt thereof; 25. the compound according to any one of 1-10 and 14-24, wherein the compound represented by the formula (1) is a compound represented by the formula (4):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (5):

wherein the bond between C and C is a disulfide bond, or a pharmaceutically acceptable salt thereof; 26. the compound according to any one of 1-10, 14 and 15, wherein when X^(b) is a divalent peptide group consisting of 2 amino acid residues containing a cysteine residue and Y^(b) is a single bond, or X^(b) is a single bond and Y^(b) is a divalent peptide group consisting of 2 amino acid residues containing a cysteine residue, a thioether group in the cysteine residue of X^(t) or a thioether group in the cysteine residue of Y^(b) binds to a thioether group in the formula (20):

wherein X^(e) and Y^(e) are each independently a single bond or a divalent peptide group consisting of 1-4 amino acid residues, and a total of the amino acid residue number for X^(e) and the amino acid residue number for Y is an integer of 0-4, cancer antigen peptide E is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues, a carbonyl group of a C-terminal amino acid of the cancer antigen peptide E binds to X^(e) in the formula (20), and an amino group of an N-terminal amino acid of the cancer antigen peptide E binds to a hydrogen atom in the formula (20), or a pharmaceutically acceptable salt thereof; 27. the compound according to 26, wherein X^(b) is a divalent dipeptide group consisting of CA and Y^(b) is a single bond, or X^(b) is a single bond and Y^(b) is a divalent dipeptide group consisting of CA, or a pharmaceutically acceptable salt thereof; 28. the compound according to 26 or 27, wherein the cancer antigen peptide B is an MHC class I-restricted cancer antigen peptide consisting of 7-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 29. the compound according to any one of 26-28, wherein the cancer antigen peptide B consists of 7-15 amino acid residues and is an HLA-A, HLA-B or HLA-Cw-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 30. the compound according to any one of 26-29, wherein the cancer antigen peptide B consists of 7-15 amino acid residues and is an HLA-A1, HLA-A2, HLA-A3, HLA-A11, HLA-A24, HLA-A28, HLA-A29, HLA-A31, HLA-A33, HLA-A34, HLA-A68, HLA-B7, HLA-B13, HLA-B35, HLA-B37, HLA-B44, HLA-B45, HLA-B51, HLA-B52, HLA-B53, HLA-Cw2, HLA-Cw3, HLA-Cw6, HLA-Cw7, HLA-Cw8 or HLA-Cw16-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 31. the compound according to any one of 26-30, wherein the cancer antigen peptide B is an MHC class I cancer antigen peptide derived from a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A6, MAGE-A10, MAGE-A12, BAGE, DAM-6, DAM-10, GAGE-1, GAGE-2, GAGE-3, GAGE-4, GAGE-5, GAGE-6, GAGE-7B, GAGE-8, NA88-A, NY-ESO-1, NY-ESO-1a, MART-1/Melan-A, MC1R, Gp100, PSA, PSM, Tyrosinase, Proteinase 3, TRP-1, TRP-2, ART-4, CAMEL, CEA, Ep-CAM, Cyp-B, Her2/neu, VEGFR, hTERT, hTRT, iCE, MUC1, MUC2, PRAME, P15, RU1, RU2, SART-1, SART-2, SART-3, AFP, β-Catenin, Caspase-8, CDK-4, ELF2, GnT-V, G250, HSP70-2M, HST-2, KIAA0205, MUM-1, MUM-2, MUM-3, Myosin, RAGE, SART-2, TRP-2, 707-AP, Survivin, Livin and SYT-SSX, or a pharmaceutically acceptable salt thereof; 32. the compound according to any one of 26-31, wherein the cancer antigen peptide B is a peptide comprising an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 3) NYKHCFPEI, (SEQ ID NO: 11) EYLQLVFGI, (SEQ ID NO: 13) FLWGPRALV, (SEQ ID NO: 19) GLYDGMEHL, (SEQ ID NO: 26) SLLMWITQCFL, (SEQ ID NO: 27) QLSLLMWIT, (SEQ ID NO: 29) AAGIGILTV, (SEQ ID NO: 33) LIYRRRLMK, (SEQ ID NO: 40) YMDGTMSQV, (SEQ ID NO: 41) AFLPWHRLF, (SEQ ID NO: 43) VLQELNVTV, (SEQ ID NO: 50) YLSGANLNL, (SEQ ID NO: 53) KIFGSLAFL, (SEQ ID NO: 66) AYIDFEMKI, (SEQ ID NO: 83) AYACNTSTL, (SEQ ID NO: 84) KWFPSCQFLL and (SEQ ID NO: 85) GYDQIMPKK, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 3, 11, 13, 19, 26, 27, 29, 33, 40, 41, 43, 50, 53, 66, 83, 84 and 85 but containing alteration of amino acid residue(s), and having a CTL induction activity, or a pharmaceutically acceptable salt thereof; 33. the compound according to any one of 26-32, wherein the cancer antigen peptide B is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 19) GLYDGMEHL, (SEQ ID NO: 43) VLQELNVTV and (SEQ ID NO: 53) KIFGSLAFL, or a pharmaceutically acceptable salt thereof; 34. the compound according to any one of 26-33, wherein X^(e) is a divalent peptide group consisting of 2 amino acid residues and Y^(e) is a single bond, X^(e) and Y^(e) are each independently a divalent peptide group consisting of 1 amino acid residue, X^(e) is a single bond and Y^(e) is a divalent peptide group consisting of 2 amino acid residues, X^(e) is a divalent peptide group consisting of 1 amino acid residue and Y^(e) is a single bond, X^(e) is a single bond and Y^(e) is a divalent peptide group consisting of 1 amino acid residue, or X^(e) and Y^(e) are each a single bond, or a pharmaceutically acceptable salt thereof; 35. the compound according to any one of 26-34, wherein X^(e) is a single bond, and Y^(e) is a single bond, an alanine residue, a leucine residue or a methionine residue, or a pharmaceutically acceptable salt thereof; 36. the compound according to any one of 26-34, wherein X^(e) is a single bond or a divalent peptide group consisting of 1 amino acid residue, and Y^(e) is a single bond, or a pharmaceutically acceptable salt thereof; 37. the compound according to any one of 26-36, wherein X^(e) and Y^(e) are each a single bond, or a pharmaceutically acceptable salt thereof; 38. the compound according to any one of 26-37, wherein the cancer antigen peptide E is an MHC class II-restricted cancer antigen peptide consisting of 7-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 39. the compound according to any one of 26-38, wherein the cancer antigen peptide E consists of 7-15 amino acid residues and is an HLA-DR, HLA-DQ or HLA-DP-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 40. the compound according to any one of 26-39, wherein the cancer antigen peptide E is an HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 41. the compound according to any one of 26-40, wherein the cancer antigen peptide E is a peptide comprising an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 101) AKFVAAWTLKAAA and (SEQ ID NO: 102) aKFVAAWTLKAAa, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 101 and 102 but containing alteration of amino acid residue(s), and having a helper T cell induction activity, or a pharmaceutically acceptable salt thereof; 42. the compound according to any one of 26-41, wherein the cancer antigen peptide E is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 101) AKFVAAWTLKAAA and (SEQ ID NO: 102) aKFVAAWTLKAAa, or a pharmaceutically acceptable salt thereof; 43. the compound according to any one of 1-10, 14, 15 and 26-42, wherein the compound represented by the formula (1) is a compound represented by the formula (19):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (21):

wherein the bond between C and C is a disulfide bond, or a pharmaceutically acceptable salt thereof; 44. the compound according to any one of 1-10 and 14-18, wherein the cancer antigen peptide B is an MHC class II-restricted cancer antigen peptide consisting of 7-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 45. the compound according to any one of 1-10, 14-18 and 26, wherein the cancer antigen peptide B consists of 7-15 amino acid residues and is an HLA-DR, HLA-DQ or HLA-DP-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 46. the compound according to any one of 1-10, 14-18, 44 and 45, wherein the cancer antigen peptide B is an HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 47. the compound according to any one of 1-10, 14-18 and 44-46, wherein the cancer antigen peptide B is a peptide comprising an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 101) AKFVAAWTLKAAA and (SEQ ID NO: 102) aKFVAAWTLKAAa, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 101 and 102 but containing alteration of amino acid residue(s), and having a helper T cell induction activity, or a pharmaceutically acceptable salt thereof; 48. the compound according to any one of 1-10, 14-18 and 44-47, wherein the cancer antigen peptide B is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 101) AKFVAAWTLKAAA and (SEQ ID NO: 102) aKFVAAWTLKAAa, or a pharmaceutically acceptable salt thereof; 49. the compound according to any one of 1-10, 14-18 and 44-48, wherein the compound represented by the formula (1) is a compound represented by the formula (6):

wherein the bond between C and C is a disulfide bond, a compound represented by the formula (7):

wherein the bond between C and C is a disulfide bond, a compound represented by the formula (15):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (16):

wherein the bond between C and C is a disulfide bond, or a pharmaceutically acceptable salt thereof; 50. the compound according to any one of 1-10, wherein R¹ is a group represented by the formula (3), or a pharmaceutically acceptable salt thereof; 51. the compound according to any one of 1-10 and 50, wherein X^(c) is a divalent peptide group consisting of 2 amino acid residues and Y^(c) is a single bond, X^(c) and Y^(c) are each independently a divalent peptide group consisting of 1 amino acid residue, X^(c) is a single bond and Y^(c) is a divalent peptide group consisting of 2 amino acid residues, X^(c) is a divalent peptide group consisting of 1 amino acid residue and Y^(c) is a single bond, X^(c) is a single bond and Y^(c) is a divalent peptide group consisting of 1 amino acid residue, or X^(c) and Y^(c) are each a single bond, or a pharmaceutically acceptable salt thereof; 52. the compound according to any one of 1-10, 50 and 51, wherein X^(c) is a single bond, and Y^(c) is a single bond, an alanine residue, a leucine residue or a methionine residue, or a pharmaceutically acceptable salt thereof; 53. the compound according to any one of 1-10, 50 and 51, wherein X^(c) is a single bond or a divalent peptide group consisting of 1 amino acid residue, and Y^(c) is a single bond, or a pharmaceutically acceptable salt thereof; 54. the compound according to any one of 1-10 and 50-53, wherein X^(c) and Y^(c) are each a single bond, or a pharmaceutically acceptable salt thereof; 55. the compound according to any one of 1-10 and 50-54, wherein the cancer antigen peptide C is an MHC class II-restricted cancer antigen peptide consisting of 7-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 56. the compound according to any one of 1-10 and 50-55, wherein the cancer antigen peptide C consists of 7-15 amino acid residues and is an HLA-DR, HLA-DQ or HLA-DP-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 57. the compound according to any one of 1-10 and 50-56, wherein the cancer antigen peptide C is an HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 58. the compound according to any one of 1-10 and 50-57, wherein the cancer antigen peptide C is a peptide comprising an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 101) AKFVAAWTLKAAA and (SEQ ID NO: 102) aKFVAAWTLKAAa, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 101 and 102 but containing alteration of amino acid residue(s), and having a helper T cell induction activity, or a pharmaceutically acceptable salt thereof; 59. the compound according to any one of 1-10 and 50-58, wherein the cancer antigen peptide C is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 101) AKFVAAWTLKAAA and (SEQ ID NO: 102) aKFVAAWTLKAAa, or a pharmaceutically acceptable salt thereof; 60. the compound according to any one of 1-10, and 50-59, wherein the compound represented by the formula (1) is a compound represented by the formula (8):

wherein the bond between C and C is a disulfide bond, a compound represented by the formula (9):

wherein the bond between C and C is a disulfide bond, a compound represented by the formula (18):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (17):

wherein the bond between C and C is a disulfide bond, or a pharmaceutically acceptable salt thereof; 61. the compound according to any one of 1-10, wherein R¹ is cancer antigen peptide D, or a pharmaceutically acceptable salt thereof; 62. the compound according to any one of 1-10 and 61, wherein the cancer antigen peptide D is an MHC class I-restricted cancer antigen peptide consisting of 7-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 63. the compound according to any one of 1-10, 61 and 62, wherein the cancer antigen peptide D consists of 7-15 amino acid residues and is an HLA-A, HLA-B or HLA-Cw-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 64. the compound according to any one of 1-10 and 61-63, wherein the cancer antigen peptide D consists of 7-15 amino acid residues and is an HLA-A1, HLA-A2, HLA-A3, HLA-A11, HLA-A24, HLA-A28, HLA-A29, HLA-A31, HLA-A33, HLA-A34, HLA-A68, HLA-B7, HLA-B13, HLA-B35, HLA-B37, HLA-B44, HLA-B45, HLA-B51, HLA-B52, HLA-B53, HLA-Cw2, HLA-Cw3, HLA-Cw6, HLA-Cw7, HLA-Cw8 or HLA-Cw16-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 65. the compound according to any one of 1-10 and 61-64, wherein the cancer antigen peptide D is an MHC class I cancer antigen peptide derived from a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A6, MAGE-A10, MAGE-A12, BAGE, DAM-6, DAM-10, GAGE-1, GAGE-2, GAGE-3, GAGE-4, GAGE-5, GAGE-6, GAGE-7B, GAGE-8, NA88-A, NY-ESO-1, NY-ESO-1a, MART-1/Melan-A, MC1R, Gp100, PSA, PSM, Tyrosinase, Proteinase 3, TRP-1, TRP-2, ART-4, CAMEL, CEA, Ep-CAM, Cyp-B, Her2/neu, VEGFR, hTERT, hTRT, iCE, MUC1, MUC2, PRAME, P15, RU1, RU2, SART-1, SART-2, SART-3, AFP, β-Catenin, Caspase-8, CDK-4, ELF2, GnT-V, G250, HSP70-2M, HST-2, KIAA0205, MUM-1, MUM-2, MUM-3, Myosin, RAGE, SART-2, TRP-2, 707-AP, Survivin, Livin and SYT-SSX, or a pharmaceutically acceptable salt thereof; 66. the compound according to any one of 1-10 and 61-65, wherein the cancer antigen peptide D is a peptide comprising an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 87) VYGFVRACL and (SEQ ID NO: 88) SLLMWITQC, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 87 and 88 but containing alteration of amino acid residue(s), and having a CTL induction activity, or a pharmaceutically acceptable salt thereof; 67. the compound according to any one of 1-10 and 61-66, wherein the cancer antigen peptide D is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 87) VYGFVRACL and (SEQ ID NO: 88) SLLMWITQC, or a pharmaceutically acceptable salt thereof; 68. the compound according to any one of 1-10 and 61-67, wherein the compound represented by the formula (1) is a compound represented by the formula (10):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (11):

wherein the bond between C and C is a disulfide bond, or a pharmaceutically acceptable salt thereof; 69. the compound according to any one of 1-10 and 61, wherein the cancer antigen peptide D is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues, or a pharmaceutically acceptable salt thereof; 70. the compound according to any one of 1-10, 61 and 69, wherein the cancer antigen peptide D consists of 13-15 amino acid residues and is an HLA-DR, HLA-DQ or HLA-DP-restricted cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 71. the compound according to any one of 1-10, 61, 69 and 70, wherein the cancer antigen peptide D is an HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues, or a pharmaceutically acceptable salt thereof; 72. the compound according to any one of 1-10, 61 and 69-71, wherein the cancer antigen peptide D is a peptide comprising the following amino acid sequence:

(SEQ ID NO: 103) aK-Cha-VAAWTLKAAa-Ahx-C, or a peptide comprising an altered amino acid sequence which is the amino acid sequence of SEQ ID NO: 103 but containing alteration of amino acid residue(s), and having a helper T cell induction activity, or a pharmaceutically acceptable salt thereof; 73. the compound according to any one of 1-10, 61 and 69-72, wherein the cancer antigen peptide D is a peptide consisting of the following amino acid sequence:

(SEQ ID NO: 103) aK-Cha-VAAWTLKAAa-Ahx-C, or a pharmaceutically acceptable salt thereof; 74. the compound according to any one of 1-10, 61 and 69-73, wherein the compound represented by the formula (1) is a compound represented by the formula (12):

wherein the bond between C and C is a disulfide bond, or a pharmaceutically acceptable salt thereof; 75. the compound according to any one of 1-10, 61, 69 and 70, wherein the cancer antigen peptide D is an MHC class II cancer antigen peptide derived from a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A6, NY-ESO-1, MART-1/Melan-A, Gp100, PSA, Tyrosinase, CEA, HER-2/neu, hTERT, MUC1 and SART-3, or a pharmaceutically acceptable salt thereof; 76. the compound according to any one of 1-10, 61, 69, 70 and 75, wherein the cancer antigen peptide D is a peptide comprising an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 104) AADHRQLQLSISSCLQQ, (SEQ ID NO: 105) RNGYRALMDKSLHVGTQCALTRR, (SEQ ID NO: 106) KKLQCVQLHVISM and (SEQ ID NO: 107) GSYVSRLLGICL, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 104, 105, 106 and 107 but containing alteration of amino acid residue(s), and having a helper T cell induction activity, or a pharmaceutically acceptable salt thereof; 77. the compound according to any one of 1-10, 61, 69, 70, 75 and 76, wherein the cancer antigen peptide D is a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 104) AADHRQLQLSISSCLQQ, (SEQ ID NO: 105) RNGYRALMDKSLHVGTQCALTRR, (SEQ ID NO: 106) KKLQCVQLHVISM and (SEQ ID NO: 107) GSYVSRLLGICL, or a pharmaceutically acceptable salt thereof; 78. the compound according to any one of 1-77, wherein the cancer antigen peptide A, the cancer antigen peptide B, the cancer antigen peptide C, or/and the cancer antigen peptide D is not a WT1 protein-derived cancer antigen peptide, or a pharmaceutically acceptable salt thereof; 79. a pharmaceutical composition comprising the compound according to any one of 1-78, or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier; 80. the pharmaceutical composition according to 79, which is used as a cancer vaccine; 81. use of the compound according to any one of 1-78, or a pharmaceutically acceptable salt thereof for the production of a cancer vaccine; 82. a method of treating or preventing cancer, comprising administering a therapeutically or prophylactically effective amount of the compound of any one of 1-78 or a pharmaceutically acceptable salt thereof to a cancer patient positive for a cancer antigen protein in need thereof; 83. a method of obtaining two different MHC class I-restricted epitopes, or an MHC class I-restricted epitope and an MHC class II-restricted epitope, comprising reacting the compound according to any one of 1-78 or a pharmaceutically acceptable salt thereof with ERAP1; and 84. a method of synthesizing a compound, comprising the following steps: (1) a step of synthesizing, by using Fmoc-C(Mmt)A-SBn and cancer antigen peptide B wherein one cysteine residue is bonded to the N-terminal, a peptide wherein a carbonyl group of the C-terminal amino acid of C(Mmt)A and an amino group of an N-terminal amino acid bonded to the N-terminal of the cancer antigen peptide B are bonded, wherein the cancer antigen peptide B is an MHC class I-restricted cancer antigen peptide consisting of 7-15 amino acid residues, (2) a step of synthesizing, by using the peptide obtained in the step (1) and cancer antigen peptide A wherein one cysteine residue protected by SPy group is bonded to the N-terminal, a peptide wherein a thioether group of the cysteine residue bonded to the N-terminal of the cancer antigen peptide B in the peptide obtained in the step (1), and a thioether group of the cysteine residue bonded to the N-terminal of the cancer antigen peptide A are bonded, wherein the cancer antigen peptide A is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues, and (3) a step of synthesizing, by using the peptide obtained in the step (2) and cancer antigen peptide E wherein one cysteine residue protected by Spy group is bonded to the C-terminal, a peptide wherein a thioether group of the cysteine residue bonded to the N-terminal of the cancer antigen peptide A in the peptide obtained in the step (2), and a thioether group of the cysteine residue bonded to the C-terminal of the cancer antigen peptide E are bonded, wherein the cancer antigen peptide E is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues.

Effect of the Invention

According to the present invention, it becomes possible to provide the aforementioned compound represented by the formula (1) useful as a cancer immunotherapeutic agent (hereinafter sometimes to be referred to as the compound of the present invention). The compound of the present invention can provide cancer vaccines and cancer immunotherapeutic agents that efficiently induce CTLs in vivo and in vitro. To be specific, the compound of the present invention enables production of two MHC class I-restricted cancer antigen peptides having different sequences or two MHC class I-restricted cancer antigen epitopes having different sequences; an MHC class I-cancer antigen restricted peptide and an MHC class II-restricted cancer antigen peptide; or an MHC class I-cancer antigen restricted cancer antigen epitope and an MHC class II-restricted cancer antigen epitope, in vivo and in vitro, and efficient induction of CTLs.

As for the HLA subtypes of two MHC class I-restricted peptides having different sequences, the compound (conjugate) of the present invention obtained by combining A02 type (such as A-0201 and A0206) peptide and A24 type (such as A-2402) peptide is particularly preferable. In Europeans and Americans (Caucasian), the population of HLA-A0201 subtype or HLA-A0206 subtype is the highest and about 47%, then HLA-A2402 subtype is about 13%, and the total of these subtypes occupies about 56%, excluding duplicates (i.e., duplicate calculation of humans having both subtypes) (Human Immunol. 62:1009; 2001). In Japanese people and the like, the population of HLA-A2402 is the highest and about 60%, then HLA-A0201 or HLA-A0206 is about 39%, and the total of these subtypes occupies about 81%, excluding duplicates (i.e., duplicate calculation of humans having both subtypes) (www.bmdc.irc.or.jp/GF-A.htm). Therefore, one of the advantages of the compound of the present invention is, specifically, that a larger population is covered by a single compound of the present invention, and selection of the HLA subtype of the patients before administration is not always essential.

Moreover, the compound of the present invention can provide an active ingredient of a cancer vaccine that is superior in physicochemical properties and stability and easily produced. As a result, formulation of cancer vaccines has been facilitated.

Specifically, examples of the physicochemical properties include solubility, viscosity of solution, easy purification resulting from such properties, easy handling after freeze-drying, and easy purification resulting from such properties. The stability includes stability after salt substitution, hygroscopicity, thermal stability, and stability after emulsion formation. Further, examples of pharmacological activities include efficacy as a cancer vaccine, difference depending on API (Active Pharmaceutical Ingredient), and interaction with additives in the preparation. Of these, the difference depending on API is a difference as a cancer vaccine due to API. Specifically, when two APIs having vastly different solubilities are used, API with smaller solubility is prone to precipitate, and it is easily expected that a sterilization treatment by filtration with a membrane filter, which is an essential requirement for pharmaceutical products, cannot be performed. Even if a sterilization treatment by filtration of API with small solubility is barely possible, it is considered that the amount of API contained in the filtrate markedly decreases and CTL induction ability essential for a cancer vaccine markedly decreases. Therefore, it is easily predicted that API with small solubility has a demerit of markedly decreased production efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a Figure showing the test results of Experimental Example 2 that examined the time-dependent change of N-terminal amino acid trimming by ERAP1 of each peptide of SEQ ID NOs: 100, 99 and 98 synthesized in Examples 1, 21 and 25.

FIG. 2 is a Figure showing the test results of Experimental Example 2 that examined the time-dependent change of N-terminal amino acid trimming by ERAP1 of each peptide of SEQ ID NOs: 95, 92 and 89 synthesized in Examples 2, 22 and 26.

FIG. 3 is a Figure showing the test results of Experimental Example 2 that examined the time-dependent change of N-terminal amino acid trimming by ERAP1 of each peptide of SEQ ID NOs: 96, 93 and 90 synthesized in Examples 11, 23 and 27.

FIG. 4 is a Figure showing the test results of Experimental Example 2 that examined the time-dependent change of N-terminal amino acid trimming by ERAP1 of each peptide of SEQ ID NOs: 97, 94 and 91 synthesized in Examples 12, 24 and 28.

FIG. 5 is a Figure showing the test results of Experimental Example 3 that examined the in vivo CTL induction ability of peptide of SEQ ID NO: 100 synthesized in Example 1, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 6 is a Figure showing the test results of Experimental Example 3 that examined the in vivo CTL induction ability of peptide of SEQ ID NO: 99 synthesized in Example 21, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 7 is a Figure showing the test results of Experimental Example 3 that examined the in vivo CTL induction ability of peptide of SEQ ID NO: 98 synthesized in Example 25, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 8 is a Figure showing the test results of Experimental Example 4 that examined the in vivo CTL induction ability of a compound represented by the formula (4) synthesized in Example 29, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 9 is a Figure showing the test results of Experimental Example 5 that examined the in vivo CTL induction ability of a compound represented by the formula (10) synthesized in Example 30, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 10 is a Figure showing the test results of Experimental Example 5 that examined the in vivo CTL induction ability of a compound represented by the formula (10) synthesized in Example 30, by IFNγ ELISPOT assay using HLA-A2402 transgenic mouse.

FIG. 11 is a Figure showing the test results of Experimental Example 13 that examined the in vivo CTL induction ability of a compound represented by the formula (11) synthesized in Example 109, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 12 is a Figure showing the test results of Experimental Example 14 that examined the in vivo CTL induction ability of a compound represented by the formula (5) synthesized in Example 110, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 13 is a Figure showing the test results of Experimental Example 19 that examined the in vivo CTL induction ability of a compound represented by the formula (16) synthesized in Example 112, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 14 is a Figure showing the test results of Experimental Example 20 that examined the in vivo CTL induction ability of a compound represented by the formula (17) synthesized in Example 113, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 15 is a Figure showing the test results of Experimental Example 21 that examined the in vivo CTL induction ability of a compound represented by the formula (18) synthesized in Example 147, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 16 is a Figure showing the test results of Experimental Example 22 that examined the in vivo CTL induction ability of a compound represented by the formula (15) synthesized in Example 111, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 17 is a Figure showing the test results of Experimental Example 23 that examined the in vivo CTL induction ability of a compound represented by the formula (19) synthesized in Example 149 in the pulsed or non-pulsed state with peptide of SEQ ID NO: 19, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 18 is a Figure showing the test results of Experimental Example 23 that examined the in vivo CTL induction ability of a compound represented by the formula (19) synthesized in Example 149 in the pulsed or non-pulsed state with peptide of SEQ ID NO: 53, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 19 is a Figure showing the test results of Comparative Example 1 that examined the in vivo CTL induction ability of peptides shown by SEQ ID NOs: 231 and 232 synthesized in Reference Examples 2 and 3 in the pulsed or non-pulsed state with peptide of SEQ ID NO: 19, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 20 is a Figure showing the test results of Comparative Example 1 that examined the in vivo CTL induction ability of peptides shown by SEQ ID NOs: 231 and 232 synthesized in Reference Examples 2 and 3 in the pulsed or non-pulsed state with peptide of SEQ ID NO: 53, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 21 is a Figure showing the test results of Comparative Example 2 that examined the in vivo CTL induction ability of peptides shown by SEQ ID NOs: 233 and 234 synthesized in Reference Examples 4 and 5 in the pulsed or non-pulsed state with peptide of SEQ ID NO: 19, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

FIG. 22 is a Figure showing the test results of Comparative Example 2 that examined the in vivo CTL induction ability of peptides shown by SEQ ID NOs: 233 and 234 synthesized in Reference Examples 4 and 5 in the pulsed or non-pulsed state with peptide of SEQ ID NO: 53, by IFNγ ELISPOT assay using HLA-A0201 transgenic mouse.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are explained in detail in the following.

The “amino acid residue” in the present invention means a region corresponding to one unit of amino acids constituting a peptide or protein in a peptide or protein molecule. Examples of the “amino acid residue” include natural or non-natural α-amino acid residue, β-amino acid residue, γ-amino acid residue or δ-amino acid residue. Specific examples thereof include natural α-amino acid residue, ornithine residue, homoserine residue, homocysteine residue, β-alanine, γ-aminobutanoic acid and δ-aminopentanoic acid. When the “amino acid residue” can be an optically active substance, it may be any of an L-form and a D-form, and an L-form is preferable.

When the “amino acid residue” in the present invention is shown in abbreviation, the following abbreviations are used.

Ala or A: alanine residue a: D-alanine residue Arg or R: arginine residue Asn or N: asparagine residue Asp or D: aspartic acid residue Cys or C: cysteine residue Gln or Q: glutamine residue Glu or E: glutamic acid residue Gly or G: glycine residue His or H: histidine residue Ile or I: isoleucine residue Leu or L: leucine residue Lys or K: lysine residue Met or M: methionine residue Phe or F: phenylalanine residue Pro or P: proline residue Ser or S: serine residue Thr or T: threonine residue Trp or W: tryptophan residue Tyr or Y: tyrosine residue Val or V: valine residue Abu: 2-aminobutyric acid residue (to be also referred to as α-aminobutyric acid residue) Orn: ornithine residue Cit: citrulline residue Cha: cyclohexylalanine residue Ahx: 2-aminohexanoic acid residue

The amino acid sequence of the “peptide” in the present invention is described according to the conventional method, wherein the amino acid residue of the N-terminal amino acid is positioned on the left side, and the amino acid residue of the C-terminal amino acid is positioned on the right side. In the “peptide”, unless particularly indicated, the amino group of the amino acid residue of the N-terminal amino acid is bonded to hydrogen atom, and the carbonyl group of the amino acid residue of the C-terminal amino acid is bonded to hydroxyl group. The divalent group of peptide means a group bonding via the amino group of the amino acid residue of the N-terminal amino acid and the carbonyl group of the amino acid residue of the C-terminal amino acid.

Also in the peptide that is a partial structure of the compound of the present invention, for example, the compounds represented by the formulae (4)-(12), unless particularly indicated, the amino group of the amino acid residue of the N-terminal amino acid is bonded to hydrogen atom, and the carbonyl group of the amino acid residue of the C-terminal amino acid is bonded to hydroxyl group.

“X^(a)” and “Y^(a)” in the present invention mean, independently, a single bond or a divalent group of peptides consisting of 1-4 amino acid residues. The sum of the amino acid residue number of X^(a) and that of Y^(a) is an integer of 0-4. For example, an integer of the sum being 0 means that X^(a) and Y^(a) are each a single bond. When the sum is an integer of 4, examples of X^(a) and Y^(a) include X^(a) and Y^(a) independently being divalent groups of peptide consisting of 2 amino acid residues, X^(a) being a divalent group of peptide consisting of 3 amino acid residues and Y^(a) being a divalent group of peptide consisting of 1 amino acid residue, and X^(a) being a divalent group of peptide consisting of 4 amino acid residues and Y^(a) being a single bond.

The integer of the sum is preferably 0-2, more preferably 0-1, most preferably 0. That is, X^(a) and Y^(a) are most preferably single bonds.

When the sum is an integer of 2, examples of X^(a) and Y^(a) include X^(a) being a divalent group of peptide consisting of 2 amino acid residues and Y^(a) being a single bond, X^(a) and Y^(a) independently being divalent groups of peptide consisting of 1 amino acid residue, and X^(a) being a single bond and Y^(a) being a divalent group of peptide consisting of 2 amino acid residues.

When the sum is an integer of 1, examples of X^(a) and Y^(a) include X^(a) being a divalent group of peptide consisting of 1 amino acid residue and Y^(a) being a single bond, and X^(a) being a single bond and Y^(a) being a divalent group of peptide consisting of 1 amino acid residue. Of these, preferred is X^(a) being a single bond and Y^(a) being an alanine residue, a leucine residue or a methionine residue, or X^(a) being an alanine residue, a glycine residue, a serine residue or a tyrosine residue and Y^(a) being a single bond.

The “cancer antigen peptide A” in the present invention is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues. In cancer antigen peptide A in the formula (1), the amino group of the N-terminal amino acid is bonded to Y^(a) in the formula (1) and the carbonyl group of the C-terminal amino acid is bonded to the hydroxyl group in the formula (1).

The term “MHC class I-restricted” in the present invention means the property to induce CTLs by binding to an MHC class I molecule, which is class I of the major histocompatibility complex (MHC).

MHC in human is called human leukocyte-type antigen (HLA). HLA corresponding to the MHC class I-molecule is classified into subtypes such as HLA-A, B, Cw, F and G. Preferable examples of the “MHC class I-restricted” peptides include HLA-A-restricted peptides, HLA-B-restricted peptides, and HLA-Cw-restricted peptides.

Polymorphism (allele) of each subtype of HLA is known. Examples of the polymorphism of HLA-A include not less than 27 kinds such as HLA-A1, HLA-A0201, and HLA-A24, examples of the polymorphism of HLA-B include not less than 59 kinds such as HLA-B7, HLA-B40, and HLA-B4403, and examples of the polymorphism of HLA-Cw include not less than 10 kinds such as HLA-Cw0301, HLA-Cw0401, and HLA-Cw0602. Among these polymorphisms, HLA-A0201 and HLA-A24 are preferable.

As the cancer antigen peptide A, an HLA-A, HLA-B or HLA-Cw-restricted cancer antigen peptide consisting of 7-15 amino acid residues is preferable, and an HLA-A1, HLA-A2, HLA-A3, HLA-A11, HLA-A24, HLA-A28, HLA-A29, HLA-A31, HLA-A33, HLA-A34, HLA-A68, HLA-B7, HLA-B13, HLA-B35, HLA-B37, HLA-B44, HLA-B45, HLA-B51, HLA-B52, HLA-B53, HLA-Cw2, HLA-Cw3, HLA-Cw6, HLA-Cw7, HLA-Cw8 or HLA-Cw16-restricted cancer antigen peptide consisting of 7-15 amino acid residues is more preferable.

The “cancer antigen peptide” in the present invention means a partial peptide of a known human cancer antigen protein. Specifically, the cancer antigen peptide is a partial peptide consisting of continuous 7-30 amino acid residues in the amino acid sequence of a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A6, MAGE-A10, MAGE-A12, BAGE, DAM-6, DAM-10, GAGE-1, GAGE-2, GAGE-3, GAGE-4, GAGE-5, GAGE-6, GAGE-7B, GAGE-8, NA88-A, NY-ESO-1, NY-ESO-1a, MART-1/Melan-A, MC1R, Gp100, PSA, PSM, Tyrosinase, Proteinase 3, TRP-1, TRP-2, ART-4, CAMEL, CEA, Ep-CAM, Cyp-B, Her2/neu, VEGFR, hTERT, hTRT, iCE, MUC1, MUC2, PRAME, P15, RU1, RU2, SART-1, SART-2, SART-3, AFP, β-Catenin, Caspase-8, CDK-4, ELF2, GnT-V, G250, HSP70-2M, HST-2, KIAA0205, MUM-1, MUM-2, MUM-3, Myosin, RAGE, SART-2, TRP-2, 707-AP, Survivin, Livin and SYT-SSX.

However, human WT1 protein (Cell, 60: 509, 1990, GenBank Acc. No. A38080) is not included in the “cancer antigen peptide” in the present invention. That is, in the compound of the present invention, the cancer antigen peptide A, the cancer antigen peptide B, the cancer antigen peptide C, or/and the cancer antigen peptide D are not WT1 protein-derived cancer antigen peptides. It is more preferable that the cancer antigen peptide A, the cancer antigen peptide B, the cancer antigen peptide C or the cancer antigen peptide D is not a WT1 protein-derived cancer antigen peptide. It is further preferable that the cancer antigen peptide A, the cancer antigen peptide B, the cancer antigen peptide C and the cancer antigen peptide D are not WT1 protein-derived cancer antigen peptides.

Specifically, in the compound represented by the formula (1) shown in item 1 above, it is preferable that: the cancer antigen peptide A is an MHC class I-restricted cancer antigen peptide consisting of continuous 7-30 amino acid residues in the amino acid sequence of a cancer antigen protein and different from a WT1 protein-derived cancer antigen peptide; and when R¹ is a group represented by the formula (2), the cancer antigen peptide B is an MHC class I or MHC class II-restricted cancer antigen peptide consisting of continuous 7-30 amino acid residues in the amino acid sequence of a cancer antigen protein and different from a WT1 protein-derived cancer antigen peptide; when R¹ is a group represented by the formula (3), the cancer antigen peptide C is an MHC class II-restricted cancer antigen peptide consisting of continuous 7-30 amino acid residues in the amino acid sequence of a cancer antigen protein and different from a WT1 protein-derived cancer antigen peptide; and when R¹ is cancer antigen peptide D, the cancer antigen peptide D is an MHC class I or MHC class II-restricted cancer antigen peptide consisting of continuous 7-30 amino acid residues in the amino acid sequence of a cancer antigen protein and different from a WT1 protein-derived cancer antigen peptide.

Therefore, the “MHC class I-restricted cancer antigen peptide” in the present invention is a peptide that binds to an MHC class I antigen in vitro and/or in vivo and is presented as a complex, and induces CTLs as a result of recognition of the complex by precursor T cells. The number of the amino acid residues of the “MHC class I-restricted cancer antigen peptide” is 7-30, preferably 7-15, more preferably 8-12, further preferably 8-11, most preferably 8 or 9.

The “MHC class I-restricted cancer antigen peptide” consisting of 7-12 or preferably 9 amino acid residues is also called “an MHC class I-restricted cancer antigen epitope”. The “MHC class I-restricted cancer antigen epitope” in the present invention means a peptide per se that binds to an MHC class I antigen and is presented as a complex. That is, “MHC class I-restricted cancer antigen peptide” produces “MHC class I-restricted cancer antigen epitope” in vitro and/or in vivo, from intracellular degradation of the compound of the present invention by proteosome and/or protease such as Gamma-Interferon-inducible Lysosomal Thiol Reductase (GILT, GLT) (proteolysis, reductive cleavage of disulfide bond), and/or cleavage into the optimal residue number (also called trimming) by Endoplasmic reticulum aminopeptidase 1 (ERAP1, ER-aminopeptidase 1). This production is mainly considered to comprise a production process wherein the C-terminal amino acid of the “MHC class I-restricted cancer antigen epitope” first results from the degradation by proteosome and/or protease, after which N-terminal amino acid of the “MHC class I-restricted cancer antigen epitope” results from trimming (cleavage) by ERAP1. In this production, however, a process other than this production process is also possible. At present, ERAP1 is also referred to as ERAAP (ER aminopeptidase associated with antigen presentation), and used to be also called A-LAP, PILS-AP or ARTS-1.

Therefore, the “MHC class I-restricted cancer antigen peptide” is preferably a peptide consisting of 7-30 amino acid residues produced by adding 1-23 amino acid residues to the carbonyl group of the C-terminal amino acid of the “MHC class I-restricted cancer antigen epitope” consisting of 7-12 amino acid residues.

Examples of the “MHC class I-restricted cancer antigen peptide” include peptides described in Tables 1-9.

The peptide of SEQ ID NO: 8 and the peptide of SEQ ID NO: 9 in Table 1 consist of the same amino acid sequence and are identical to each other. The peptide is an HLA-Cw3-restricted cancer antigen peptide, and also an HLA-Cw16-restricted cancer antigen peptide.

TABLE 1 cancer antigen HLA SEQ ID protein type amino acid sequence NO: MAGE-A1 A1 EADPTGHYS  1 MAGE-A1 A3 SLFRAVITK  2 MAGE-A1 A24 NYKHCFPEI  3 MAGE-A1 A28 EVYDGREHSA  4 MAGE-A1, B37 REPVTKAEML  5 2, 3, 6 MAGE-A1 B53 DPARYEFLW  6 MAGE-A1 Cw2 SAFPTTINF  7 MAGE-A1 Cw3 SAYGEPRKL  8 MAGE-A1 Cw16 SAYGEPRKL  9 MAGE-A2 A2 KMVELVHFL 10

TABLE 2 cancer SEQ antigen HLA ID protein type amino acid sequence NO: MAGE-A2 A24 EYLQLVFGI 11 MAGE-A3 A1 EADPIGHLY 12 MAGE-A3 A2 FLWGPRALV 13 MAGE-A3 A24 TFPDLESEF 14 MAGE-A3 B44 MEVDPIGHLY 15 MAGE-A3 B52 WQYFFPVIF 16 MAGE-A4 A2 GVYDGREHTV 17 MAGE-A6 A34 MVKISGGPR 18 MAGE-A10 A2 GLYDGMEHL 19 MAGE-A12 Cw7 VRIGHLYIL 20

TABLE 3 cancer SEQ antigen HLA ID protein type amino acid sequence NO: BAGE Cw16 AARAVFLAL 21 DAM-6, 10 A2 FLWGPRAYA 22 GAGE-1, 23 2, 8 Cw6 YRPRPRRY GAGE-3, 4, A29 YYWPRPRRY 24 5, 6, 7B NA88-A B13 MTQGQHFLQKV 25 NY-ESO-1 A2 SLLMWITQCFL 26 NY-ESO-1a A2 QLWLLMWIT 27 NY-ESO-1a A31 ASGPGGGAPR 28 MART-1/ A2 AAGIGILTV 29 Melan-A MART-1/ B45 AEEAAGIGIL 30 Melan-A

TABLE 4 cancer SEQ antigen HLA ID protein type amino acid sequence NO: MC1R A2 TILLGIFFL 31 Gp100 A2 KTWGQYWQV 32 Gp100 A3 LIYRRRLMK 33 Gp100 A24 VYFFLPDHL 34 Gp100 Cw8 SNDGPTLI 35 PSA A1 VSHSFPHPLY 36 PSA A2 FLTPKKLQCV 37 PSM A1 HSTNGVTRIY 38 Tyrosinase A1 KCDICTDEY 39 Tyrosinase A2 YMDGTMSQV 40

TABLE 5 cancer SEQ antigen HLA ID protein type amino acid sequence NO: Tyrosinase A24 AFLPWHRLF 41 Tyrosinase B44 SEIWRDIDF 42 Proteinase-3 VLQELNVTV 43 TRP-1 A31 MSLQRQFLR 44 TRP-2 A2 SVYDFFVWL 45 TRP-2 A31, LLGPGRPYR 46 33 TRP-2 Cw8 ANDPIFVVL 47 ART-4 A24 AFLRHAAL 48 CAMEL A2 MLMAQEALAFL 49 CEA A2 YLSGANLNL 50

TABLE 6 cancer SEQ antigen HLA ID protein type amino acid sequence NO: CEA A3 HLFGYSWYK 51 Cyp-B A24 KFHRVIKDF 52 HER2/neu A2 KIFGSLAFL 53 HER2/neu A3 VLRENTSPK 54 hTERT A2 ILAKFLHWL 55 iCE B7 SPRWWPTCL 56 MUC1 A11 STAPPAHGV 57 MUC1 A2 STAPPVHNV 58 MUC2 A2 LLNQLQVNL 59 PRAME A24 LYVDSLFFL 60

TABLE 7 cancer SEQ antigen HLA ID protein type amino acid sequence NO: P15 A24 AYGLDFYIL 61 RU1 B51 VPYGSFKHV 62 RU2 B7 LPRWPPPQL 63 SART-1 A24 EYRGFTQDF 64 SART-2 A24 DYSARWNEI 65 SART-3 A24 AYIDFEMKI 66 AFP A2 GVALQTMKQ 67 b-Catenin A24 SYLDSGIHF 68 Caspase-8 B35 FPSDSWCYF 69 CDK-4 A2 ACDPHSGHFV 70

TABLE 8 cancer SEQ antigen HLA ID protein type amino acid sequence NO: ELF2 M A68 ETVSEQSNV 71 GnT-V A2 VLPDVFIRC 72 G250 A2 HLSTAFARV 73 HSP70-2M A2 SLFEGIDIY 74 HST-2 A31 YSWMDISCWI 75 MUM-1 B44 EEKLIVVLF 76 MUM-2 B44 SELFRSGLDY 77 MUM-2 Cw6 FRSGLDSYV 78 MUM-3 A28 EAFIQPITR 79 Myosin/m A3 KINKNPKYK 80

TABLE 9 cancer SEQ antigen HLA ID protein type amino acid sequence NO: RAGE B7 SPSSNRIRNT 81 707-AP A2 RVAALARDA 82 survivin A24 AYACNTSTL 83 livin A24 KWFPSCQFLL 84 SYT-SSX A24 GYDQIMPKK 85 hTERT A24 VYGFVRACL 87 NY-ESO-1 A2 SLLMWITQC 88

Preferable examples of the “MHC class I-restricted cancer antigen peptide” include a peptide comprising an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 3) NYKHCFPEI, (SEQ ID NO: 11) EYLQLVFGI, (SEQ ID NO: 13) FLWGPRALV (SEQ ID NO: 19) GLYDGMEHL, (SEQ ID NO: 26) SLLMWITQCFL, (SEQ ID NO: 27) QLSLLMWIT, (SEQ ID NO: 29) AAGIGILTV, (SEQ ID NO: 33) LIYRRRLMK, (SEQ ID NO: 40) YMDGTMSQV, (SEQ ID NO: 41) AFLPWHRLF, (SEQ ID NO: 43) VLQELNVTV, (SEQ ID NO: 50) YLSGANLNL, (SEQ ID NO: 53) KIFGSLAFL, (SEQ ID NO: 66) AYIDFEMKI, (SEQ ID NO: 83) AYANCNTSTL, (SEQ ID NO: 84) KWFPSCQFLL, (SEQ ID NO: 85) GYDQIMPKK, (SEQ ID NO: 87) VYGFVRACL and (SEQ ID NO: 88) SLLMWITQC, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 3, 11, 13, 19, 26, 27, 29, 33, 40, 41, 43, 50, 53, 66, 83, 84, 85, 87 and 88 but contains alteration of amino acid residue(s) in the amino acid sequence, and having a CTL induction activity. As the “MHC class I-restricted cancer antigen peptide”, a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 3, 11, 13, 19, 26, 27, 29, 33, 40, 41, 43, 50, 53, 66, 83, 84, 85, 87 and 88 is more preferable, and a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 19, 43 and 53 is further preferable.

The “peptide comprising an amino acid sequence” in the present invention means, as usual, a peptide whose amino acid sequence comprises a further amino acid added to the N-terminal amino acid and/or C-terminal amino acid of the amino acid sequence. When the further amino acid is added to the “MHC class I-restricted cancer antigen peptide” for the “cancer antigen peptide A” and “cancer antigen peptide B”, the further amino acid is preferably added to the C-terminal side of the peptide.

The “peptide comprising an altered amino acid sequence that contains alteration of amino acid residue(s) in the amino acid sequence, and having a CTL induction activity” in the present invention is also called an “altered killer peptide”. The altered killer peptide means a peptide that consists of an amino acid sequence wherein 1 to 3 amino acids are deleted from, substituted in, and/or added to the original amino acid sequence, and binds to MHC class I to induce CTLs. The position of the amino acid to be substituted includes position 1 (N-terminal), position 2, position 3 or position 9 for a peptide consisting of 9 amino acid residues. The number of amino acids to be added (or inserted, since “addition” encompasses “insertion”) is preferably 1 or 2, more preferably 1. A preferable position for addition is the C-terminal. The number of amino acids to be deleted is preferably 1. In the alteration, the amino acid to be added or substituted may be a non-natural amino acid other than the 20 kinds of amino acids encoded by the gene.

“R¹” in the present invention is a hydrogen atom, a group represented by the formula (2), a group represented by the formula (3) or cancer antigen peptide D; preferably, a group represented by the formula (2), a group represented by the formula (3) or cancer antigen peptide D.

When R¹ is a hydrogen atom, the compound of the formula (1) is a compound represented by the formula (1-1):

wherein X^(a), Y^(a) and cancer antigen peptide A are as defined in the above for the formula (1), and Cys is a cysteine residue, namely, a peptide.

The compound of the formula (1) wherein R¹, is a hydrogen atom, namely, a peptide represented by the formula (1-1), has a sequence not identical to a partial sequence of a cancer antigen protein. The requirement that the sequence of the formula (1) “is not identical to a partial sequence of a cancer antigen protein” means that a peptide represented by the formula (1-1) is not a partial peptide consisting of continuous 8-35 amino acid residues in the amino acid sequence of a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A6, MAGE-A10, MAGE-A12, BAGE, DAM-6, DAM-10, GAGE-1, GAGE-2, GAGE-3, GAGE-4, GAGE-5, GAGE-6, GAGE-7B, GAGE-8, NA88-A, NY-ESO-1, NY-ESO-1a, MART-1/Melan-A, MC1R, Gp100, PSA, PSM, Tyrosinase, Proteinase 3, TRP-1, TRP-2, ART-4, CAMEL, CEA, Ep-CAM, Cyp-B, Her2/neu, VEGFR, hTERT, hTRT, iCE, MUC1, MUC2, PRAME, P15, RU1, RU2, SART-1, SART-2, SART-3, AFP, β-Catenin, Caspase-8, CDK-4, ELF2, GnT-V, G250, HSP70-2M, HST-2, KIAA0205, MUM-1, MUM-2, MUM-3, Myosin, RAGE, SART-2, TRP-2, 707-AP, Survivin, Livin and SYT-SSX.

That is, the compound of the formula (1) wherein R¹ is a hydrogen atom is not a partial peptide consisting of continuous 8-35 amino acid residues in the amino acid sequence of the aforementioned cancer antigen protein. A specific explanation is given by taking a case when the cancer antigen peptide A is a HER2/neu₃₆₉₋₃₇₇ peptide as an example. HER2/neu₃₆₉₋₃₇₇ peptide is a partial peptide consisting of continuous 9 amino acid residues at positions 369-377 of the amino acid sequence of human HER2/neu protein, and has an amino acid sequence of KIFGSLAFL (SEQ ID NO: 53). In the amino acid sequence of HER2/neu protein, the amino acid residue at position 368 continuing from the N-terminal side of HER2/neu₃₆₉₋₃₇₇ peptide is K, and the amino acid residue at position 367 further continuing therefrom is C. Therefore, HER2/neu₃₆₇₋₃₇₇ peptide (CKKIFGSLAFL) (SEQ ID NO: 86) corresponds to a partial peptide consisting of continuous 11 amino acid residues of the amino acid sequence of HER2/neu protein. On the other hand, based on the requirement of the present invention that the compound of the formula (1) wherein R¹ is a hydrogen atom is not a partial peptide consisting of continuous 8-35 amino acid residues in the amino acid sequence of a cancer antigen protein, HER2/neu₃₆₇₋₃₇₇ peptide (CKKIFGSLAFL) is excluded from the compound of the present invention. Thus, when R¹ is a hydrogen atom and the cancer antigen peptide A is HER2/neu₃₆₉₋₃₇₇ KIFGSLAFL (SEQ ID NO: 53) in the compound of the formula (1), X^(a) is not a single bond and Y^(a) is not a lysine residue. HER2/neu₃₆₇₋₃₇₇ peptide (CKKIFGSLAFL) (SEQ ID NO: 86) is not Example but is Reference Example of the present invention, as mentioned later.

For each of the peptides of SEQ ID NOs: 3, 11, 13, 19, 26, 27, 29, 33, 40, 41, 43, 50, 53, 66, 83, 84 and 85, which are preferable examples of the “MHC class I-restricted cancer antigen epitope” of the present invention, Tables 10-11 show the 5 amino acid residues continuing from the N-terminal side of the peptide in the amino acid sequence of the corresponding cancer antigen protein.

TABLE 10 5 amino acid cancer SEQ residues con- antigen amino acid ID tinuing from protein sequence NO: N-terminal side MAGE-A1 NYKHCFPEI  3 ESVIK MAGE-A2 EYLQLVFGI 11 FSKAS MAGE-A3 FLWGPRALV 13 PACYE MAGE-A10 GLYDGMEHL 19 ALNMM NY-ESO-1 SLLMWITQCFL 26 CLQQL NY-ESO-1a QLSLLMWIT 27 SSCLQ MART-1/ AAGIGILTV 29 TTAEE Melan-A Gp100 LIYRRRLMK 33 VVLAS Tyrosinase YMDGTMSQV 40 NALHI

TABLE 11 5 amino acid cancer SEQ residues con- antigen amino acid ID tinuing from protein sequence NO: N-terminal side Tyrosinase AFLPWHRLF 41 AHEAP Proteinase-3 VLQELNVTV 43 DPPAQ CEA YLSGANLNL 50 PPDSS HER2/neu KIFGSLAFL 53 FAGCK SART-3 AYIDFEMKI 66 LAEYQ survivin AYACNTSTL 83 GPGTV livin KWFPSCQFLL 84 WTEHA SYT-SSX GYDQIMPKK 85 QQRPY

Since a total of the amino acid residue number for X^(a) and the amino acid residue number for Y^(a) is an integer of 0-4, the peptide of the formula (1-1) that meets the requirement of the present invention that “the compound of the formula (1) wherein R¹ is a hydrogen atom is not a partial peptide consisting of continuous 8-35 amino acid residues in the amino acid sequence of a cancer antigen protein” can be determined easily by comparing X^(a)-Cys-Y^(a) in the formula (1-1) with, for example, the 5 amino acid residues continuing from the N-terminal side of the peptide in the amino acid sequence of the corresponding cancer antigen protein shown in Tables 10 and 11.

The compound of the formula (1) wherein R¹ is a hydrogen atom is preferably a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 89) CAGLYDGMEHL, (SEQ ID NO: 90) CLGLYDGMEHL, (SEQ ID NO: 91) CMGLYDGMEHL, (SEQ ID NO: 92) CAVLQELNVTV, (SEQ ID NO: 93) CLVLQELNVTV, (SEQ ID NO: 94) CMVLQELNVTV, (SEQ ID NO: 95) CAKIFGSLAFL, (SEQ ID NO: 96) CLKIFGSLAFL and (SEQ ID NO: 97) CMKIFGSLAFL, and further preferably a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 89-91.

The compound of the formula (1) wherein R¹ is a hydrogen atom is also preferably a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 98) CGLYDGMEHL, (SEQ ID NO: 99) CVLQELNVTV and (SEQ ID NO: 100) CKIFGSLAFL, and further preferably a peptide consisting of the amino acid sequence of SEQ ID NO: 98.

When “R¹” is a group represented by the formula (2), the compound of the formula (1) is a compound represented by the formula (1-2):

wherein X^(a), Y^(a) and cancer antigen peptide A are as defined in the above for the formula (1), and X^(b), Y^(b) and cancer antigen peptide B are as defined in the above for the formula (2).

“X^(b)” and “Y^(b)” in the present invention mean, independently, a single bond or a divalent group of peptides consisting of 1-4 amino acid residues. The sum of the amino acid residue number of X^(b) and that of Y^(b) is an integer of 0-4. For example, an integer of the sum being 0 means that X^(b) and Y^(b) are each a single bond. When the sum is an integer of 4, examples of X^(b) and Y^(b) include X^(b) and Y^(b) independently being divalent groups of peptide consisting of 2 amino acid residues, X^(b) being a divalent group of peptide consisting of 3 amino acid residues and Y^(b) being a divalent group of peptide consisting of 1 amino acid residue, and X^(b) being a divalent group of peptide consisting of 4 amino acid residues and Y^(b) being a single bond.

The integer of the sum is preferable 0-2, more preferable 0-1, most preferably 0. That is, X^(b) and Y^(b) are most preferably single bonds.

When the sum is an integer of 2, examples of X^(b) and Y^(b) include X^(b) being a divalent group of peptide consisting of 2 amino acid residues and Y^(b) being a single bond, X^(b) and Y^(h) independently being divalent groups of peptide consisting of 1 amino acid residue, and X^(b) being a single bond and Y^(b) being a divalent group of peptide consisting of 2 amino acid residues.

When the sum is an integer of 1, examples of X^(b) and Y^(b) include X^(b) being a divalent group of peptide consisting of 1 amino acid residue and Y^(b) being a single bond, and X^(b) being a single bond and Y^(b) being a divalent group of peptide consisting of 1 amino acid residue. Of these, preferred is X^(b) being a single bond and Y^(b) being an alanine residue, leucine residues or methionine residue.

The “cancer antigen peptide B” in the present invention is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues, or an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues. In the meantime, in the compound represented by the formula (1), cancer antigen peptide A and cancer antigen peptide B are not the same peptide. That is, cancer antigen peptide B is limited by the requirement that it is “different from cancer antigen peptide A”.

Since cancer antigen peptide A and cancer antigen peptide B are not the same peptide, the compound of the formula (1) wherein R¹ is a group represented by the formula (2) is not a homodimer but a heterodimer, even when X^(a) and X^(b) are the same and Y^(a) and Y^(b) are the same. Homodimer means a dimer wherein the same peptide monomers are dimerized, and heterodimer means a dimer wherein different peptide monomers are dimerized.

In the cancer antigen peptide B, the amino group of the N-terminal amino acid is bonded to Y^(b) in the formula (2) (i.e., also bonded to Y^(b) in the formula (1-2)), and the carbonyl group of the C-terminal amino acid is bonded to the hydroxyl group in the formula (2) (i.e., also bonded to the hydroxyl group in the formula (1-2)).

When the “cancer antigen peptide B” in the present invention is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues, the “MHC class I-restricted cancer antigen peptide” is as defined above.

The compound of the formula (1) wherein R¹ is a group represented by the formula (2) and cancer antigen peptide B is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues is preferably a compound represented by the formula (4):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (5):

wherein the bond between C and C is a disulfide bond.

When X^(b) is a divalent peptide group consisting of 2 amino acid residues containing a cysteine residue and Y^(b) is a single bond, or X^(b) is a single bond and Y^(b) is a divalent peptide group consisting of 2 amino acid residues containing a cysteine residue, more preferably when X^(b) is a divalent dipeptide group consisting of CA and Y^(b) is a single bond, or X^(b) is a single bond and Y^(b) is a divalent dipeptide group consisting of CA, the compound of the formula (1) may be

a compound wherein a thioether group in the cysteine residue of X^(b) or a thioether group in the cysteine residue of Y^(b) is bonded to a thioether group in the formula (20):

“X^(e)” and “Y^(e)” in the present invention mean, independently, a single bond or a divalent group of peptides consisting of 1-4 amino acid residues. The sum of the amino acid residue number of X^(e) and that of Y^(e) is an integer of 0-4. For example, an integer of the sum being 0 means that X^(e) and Y^(e) are each a single bond. When the sum is an integer of 4, examples of X^(e) and Y^(e) include X^(e) and Y^(e) independently being divalent groups of peptide consisting of 2 amino acid residues, X^(e) being a divalent group of peptide consisting of 3 amino acid residues and Y^(e) being a divalent group of peptide consisting of 1 amino acid residue, and X^(e) being a divalent group of peptide consisting of 4 amino acid residues and Y^(e) being a single bond.

The integer of the sum is preferably 0-2, more preferably 0-1, most preferably 0. That is, X^(e) and Y^(e) are most preferably single bonds.

When the sum is an integer of 2, examples of X^(e) and Y^(c) include X^(c) being a divalent group of peptide consisting of 2 amino acid residues and Y^(e) being a single bond, X^(e) and Y^(e) independently being divalent groups of peptide consisting of 1 amino acid residue, or X^(e) being a single bond and Y^(e) being a divalent group of peptide consisting of 2 amino acid residues.

When the sum is an integer of 1, examples of X^(e) and Y^(e) include X^(e) being a divalent group of peptide consisting of 1 amino acid residue and Y^(e) being a single bond, and X^(e) being a single bond and Y^(e) being a divalent group of peptide consisting of 1 amino acid residue. Of these, preferred is X^(e) being a single bond and Y^(e) being an alanine residue, leucine residues or methionine residue.

The “cancer antigen peptide E” in the present invention is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues. In the formula (20), the carbonyl group of the C-terminal amino acid of the cancer antigen peptide E is bonded to X^(c) in the formula (20), and the amino group of the N-terminal amino acid of the cancer antigen peptide E is bonded to the hydrogen atom in the formula (20).

The “MHC class II-restricted cancer antigen peptide” in the present invention is as defined for the “MHC class II-restricted cancer antigen peptide” in the below-mentioned “cancer antigen peptide B”.

HLA corresponding to the MHC class II-molecule is classified into subtypes such as HLA-DR, DQ and DP. Preferable examples of the “MHC class II-restricted” peptides include HLA-DR-restricted peptides, HLA-DQ-restricted peptides and HLA-DP-restricted peptides.

Therefore, the “MHC class II-restricted cancer antigen peptide” in the present invention is a peptide that binds to an MHC class II antigen in vitro and/or in vivo and induces helper T cells. The number of the amino acid residues of the “MHC class II-restricted cancer antigen peptide” is 7-30, preferably 14-30.

When the “cancer antigen peptide E” in the present invention is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues, the number of the amino acid residues is preferably 9-15, more preferably 13-15. As the cancer antigen peptide E, an HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues is further preferable.

The “universal cancer antigen peptide” in the present invention means a cancer antigen peptide or an epitope that binds to plural kinds of MHC class II molecules, regardless of the subtype of MHC class II or the kind of polymorphism, and induces helper T cells. The “HLA-DR-restricted universal cancer antigen peptide” is also referred to as a pan HLA-DR binding peptide.

Examples of the “cancer antigen peptide E” include, similar to the below-mentioned “cancer antigen peptide B”, a peptide consisting of an amino acid sequence selected from the following amino acid sequences:

(SEQ ID NO: 101) AKFVAAWTLKAAA, and (SEQ ID NO: 102) aKFVAAWTLKAAa.

In the compound of the formula (1-2), when X^(b) is a divalent peptide group consisting of 2 amino acid residues containing a cysteine residue and Y^(b) is a single bond, or X^(b) is a single bond and Y^(b) is a divalent peptide group consisting of 2 amino acid residues containing a cysteine residue, more preferably when X^(b) is a divalent dipeptide group consisting of CA and Y^(b) is a single bond, or X^(b) is a single bond and Y^(b) is a divalent dipeptide group consisting of CA, the compound of the formula (1-2) wherein a thioether group in the cysteine residue of X^(b) or a thioether group in the cysteine residue of Y^(b) is bonded to a thioether group in the formula (20) is preferably a compound represented by the formula (19):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (21):

wherein the bond between C and C is a disulfide bond.

The “MHC class II-restricted cancer antigen peptide” for the “cancer antigen peptide B” in the present invention is explained in the following.

In the present invention, “MHC class II-restricted” means the property to induce helper T cells by binding to an MHC class II molecule.

HLA corresponding to the MHC class II-molecule is classified into subtypes such as HLA-DR, DQ and DP. Preferable examples of the “MHC class II-restricted” peptides include HLA-DR-restricted peptides, HLA-DQ-restricted peptides, and HLA-DP-restricted peptides.

Therefore, the “MHC class II-restricted cancer antigen peptide” in the present invention is a peptide that binds to an MHC class II antigen in vitro and/or in vivo and induces helper T cells. The number of the amino acid residues of the “MHC class II-restricted cancer antigen peptide” is 7-30, preferably 14-30.

When the “cancer antigen peptide B” in the present invention is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues, the number of the amino acid residues is preferably 9-15, more preferably 13-15. As the cancer antigen peptide B, an HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues is further preferable.

The “universal cancer antigen peptide” in the present invention means a cancer antigen peptide or an epitope that binds to plural kinds of MHC class II molecules, regardless of the subtype of MHC class II or the kind of polymorphism, and induces helper T cells. The “HLA-DR-restricted universal cancer antigen peptide” is also referred to as a pan HLA-DR binding peptide.

Examples of the “HLA-DR-restricted universal cancer antigen peptide” include peptides described in Table 12.

TABLE 12 SEQ ID amino acid sequence NO: AKFVAAWTLKAAA 101 aKFVAAWTLKAAa 102

The “universal cancer antigen peptide” is preferably a peptide comprising an amino acid sequence selected from SEQ ID NOs: 101 and 102, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID Nos: 101 and 102 but containing alteration of amino acid residue(s), and having a helper T cell induction activity, and more preferable a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 101 and 102.

The definition “comprising the amino acid sequence” is as defined above. The “peptide comprising an altered amino acid sequence containing alteration of amino acid residue(s) in an amino acid sequence, and having a helper T cell induction activity” is also referred to as an “altered helper peptide”. The altered helper peptide means a peptide that consists of an amino acid sequence wherein 1 to 3 amino acids are deleted from, substituted in, and/or added to the original sequence and binds to MHC class II to induce helper T cells. The number of the amino acids to be added (or inserted, since “addition” encompasses “insertion”) is preferably 1-3. The number of the amino acids to be deleted is preferable 1-5. In the alteration, the amino acid to be added or amino acid to be substituted may be non-natural amino acid other than the 20 kinds of amino acids encoded by the gene.

The compound of the formula (1) wherein R¹ is a group represented by the formula (2) and cancer antigen peptide B is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues is preferably a compound represented by the formula (6):

wherein the bond between C and C is a disulfide bond, a compound represented by the formula (7):

wherein the bond between C and C is a disulfide bond, a compound represented by the formula (15):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (16):

wherein the bond between C and C is a disulfide bond.

When “R¹” is a group represented by the formula (3), the compound of the formula (1) is a compound represented by the formula (1-3):

wherein X^(a), Y^(a) and cancer antigen peptides A are as defined in the above for the formula (1), and X^(c), Y^(c) and cancer antigen peptide C are as defined in the above for the formula (3).

“X^(c)” and “Y^(c)” in the present invention are each independently a single bond or a divalent peptide group consisting of 1-4 amino acid residues. The sum of the amino acid residue number of X^(c) and the amino acid residue number of Y^(c) is an integer of 0-4. For example, an integer of the sum being 0 means that X^(c) and Y^(c) are each a single bond. When the sum is an integer of 4, examples of X^(c) and Y^(c) include X^(c) and Y^(c) independently being divalent groups of peptide consisting of 2 amino acid residues, X^(c) being a divalent group of peptide consisting of 3 amino acid residues and Y^(c) being a divalent group of peptide consisting of 1 amino acid residue, and X^(c) being a divalent group of peptide consisting of 4 amino acid residues and Y; being a single bond.

The integer of the sum is preferably 0-2, more preferably 0-1, most preferably 0. That is, X^(c) and Y^(c) are most preferably single bonds.

When the sum is an integer of 2, examples of X^(c) and Y^(c) include X^(c) being a divalent group of peptide consisting of 2 amino acid residues and Y^(c) being a single bond, X¹ and Y independently being divalent groups of peptide consisting of 1 amino acid residue, and X^(c) being a single bond and Y^(c) being a divalent group of peptide consisting of 2 amino acid residues.

When the sum is an integer of 1, examples of X^(c) and Y^(c) include X^(c) being a divalent group of peptide consisting of 1 amino acid residue and Y being a single bond, and X^(c) being a single bond and Y^(c) being a divalent group of peptide consisting of 1 amino acid residue. Of these, preferred is X^(c) being a single bond and Y^(c) being an alanine residue, leucine residues or methionine residue.

The “cancer antigen peptide C” in the present invention is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues. The “MHC class II-restricted cancer antigen peptide” is as defined above.

When the “cancer antigen peptide C” in the present invention is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues, the number of the amino acid residues is preferably 9-15, more preferably 13-15. As the cancer antigen peptide C, an HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues is further preferable. The “HLA-DR-restricted universal cancer antigen peptide” is as defined above.

In the cancer antigen peptide C, the carbonyl group of the C-terminal amino acid is bonded to X^(c) in the formula (3) (i.e., also bonded to X^(c) in the formula (1-3)), and the amino group of the N-terminal amino acid is bonded to the hydrogen atom in the formula (3) (i.e., also bonded to the hydrogen atom in the formula (1-3)).

The compound of the formula (1) wherein R¹ is a group represented by the formula (3) and cancer antigen peptide C is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues is preferably a compound represented by the formula (8):

wherein the bond between C and C is a disulfide bond, a compound represented by the formula (9):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (18):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (17):

When R¹ is cancer antigen peptide D, the thioether group of the cysteine residue of the cancer antigen peptide D is bonded to the thioether group in the formula (1). In the cancer antigen peptide D, the amino group of the N-terminal amino acid is bonded to the hydrogen atom, and the carbonyl group of the C-terminal amino acid is bonded to the hydroxyl group.

The cancer antigen peptide D is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue or an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue.

The “MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue” in the present invention is required to contain at least one cysteine residue in the amino acid sequence of the peptide. The number of the cysteine residues to be contained is preferably 1-3, more preferably 1-2, most preferably 1. The “MHC class I-restricted cancer antigen peptide” is as defined above. Also, the compound of the formula (1) wherein R¹ is “an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue” is not a homodimer but a heterodimer.

Examples of the “MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue” include peptides described in Table 13.

TABLE 13 cancer antigen amino acid SEQ ID protein HLA type sequence NO: MAGE-A1 A24 NYKHCFPEI  3 NY-ESO-1 A2 SLLMWITQCFL 26 PSA A2 FLTPKKLQCV 37 Tyrosinase A1 KCDICTDEY 39 iCE B7 SPRWWPTCL 56 Caspase-8 B35 FPSDSWCYF 69 CDK-4 A2 ACDPHSGHFV 70 GnT-V A2 VLPDVFIRC 72 HST-2 A31 YSWMDISCWI 75 survivin A24 AYACNTSTL 83 livin A24 KWFPSCQFLL 84 hTERT A24 VYGFVRACL 87 NY-ESO-1 A2 SLLMWITQC 88

More preferable examples of the “MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue” include a peptide comprising an amino acid sequence selected from the following amino acid sequences:

VYGFVRACL (SEQ ID NO: 87) and SLLMWITQC (SEQ ID NO: 88)

and a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 87 and 88 but containing alteration of amino acid residue(s), and having a CTL induction activity. Most preferably, a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 87 and 88 is mentioned. The definitions “comprising the amino acid sequence” and “peptide comprising an altered amino acid sequence containing alteration of amino acid residue(s) in an amino acid sequence, and having a CTL induction activity” are as defined above.

The compound of the formula (1) wherein R¹ is an “MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue” is preferably a compound represented by the formula (10):

wherein the bond between C and C is a disulfide bond, or a compound represented by the formula (11):

wherein the bond between C and C is a disulfide bond.

The “MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue” in the present invention is required to contain at least one cysteine residue in the amino acid sequence of the peptide. The number of the cysteine residues to be contained is preferably 1-3, more preferably 1-2, most preferably 1. The “MHC class II-restricted cancer antigen peptide” is as defined above.

In the “MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue”, the number of the amino acid residues is preferably 9-15, more preferably 13-15. The MHC class II-restricted peptide is preferably an HLA-DR-restricted peptide, an HLA-DQ-restricted peptide, or an HLA-DP-restricted peptide.

When the cancer antigen peptide D is an “MHC class II-restricted cancer antigen peptide consisting of 13-15 amino acid residues containing one cysteine residue”, the “MHC class II-restricted cancer antigen peptide” is preferably an HLA-DR-restricted universal cancer antigen peptide, or a cancer antigen peptide derived from a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A6, NY-ESO-1, MART-1/Melan-A, Gp100, PSA, Tyrosinase, CEA, HER-2/neu, hTERT, MUC1 and SART-3.

Examples of the “HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues containing one cysteine residue” include peptides described in Table 14.

TABLE 14 amino acid sequence SEQ ID NO: aK-Cha-VAAWTLKAAa-Ahx-C 103

The “HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues containing one cysteine residue” is preferably a peptide comprising the amino acid sequence of SEQ ID NO: 103, or a peptide comprising an altered amino acid sequence which is the amino acid sequence of SEQ ID NO: 103 but containing alteration of amino acid residue(s), and having a helper T cell induction activity, and more preferably a peptide consisting of the amino acid sequence of SEQ ID NO: 103. The definitions “comprising the amino acid sequence” and “peptide comprising an altered amino acid sequence containing alteration of amino acid residue(s) in an amino acid sequence, and having a helper T cell induction activity” are as defined above.

The compound of the formula (1) wherein R¹ is an “HLA-DR-restricted universal cancer antigen peptide consisting of 13-15 amino acid residues containing one cysteine residue” is preferably a compound represented by the formula (12):

wherein the bond between C and C is a disulfide bond.

Examples of the “cancer antigen peptide derived from a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A6, NY-ESO-1, MART-1/Melan-A, Gp100, PSA, Tyrosinase, CEA, HER-2/neu, hTERT, MUC1 and SART-3 and consisting of 13-15 amino acid residues containing one cysteine residue” include peptides described in Table 15.

TABLE 15 SEQ ID amino acid sequence NO:  AADHRQLQLSISSCLQQL 104 RNGYRALMDKSLHVGTQCALTRR 105 KKLQCVQLHVISM 106 GSYVSRLLGICL 107

The “cancer antigen peptide derived from a cancer antigen protein selected from the group consisting of MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A6, NY-ESO-1, MART-1/Melan-A, Gp100, PSA, Tyrosinase, CEA, HER-2/neu, hTERT, MUC1 and SART-3 and consisting of 13-15 amino acid residues containing one cysteine residue” is preferably a peptide comprising an amino acid sequence selected from SEQ ID NOs: 104-107, or a peptide comprising an altered amino acid sequence which is an amino acid sequence selected from SEQ ID NOs: 104-107 but containing alteration of amino acid residue(s), and having a helper T cell induction activity, and more preferably a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 104-107. The definitions “containing the amino acid sequence” and “peptide comprising an altered amino acid sequence containing alteration of amino acid residue(s) in an amino acid sequence, and having a helper T cell induction activity” are as defined above.

The present invention also provides a synthesis method of a compound wherein two different MHC class I-restricted cancer antigen peptide and MHC class II-restricted cancer antigen peptide, or two different MHC class I-restricted cancer antigen epitope and MHC class II-restricted cancer antigen epitope are each bonded via a disulfide bond. The method of the present invention includes the following steps (1)-(3).

In step (1) of the present invention, Fmoc-C(Mmt)A-SBn and cancer antigen peptide B wherein one cysteine residue is bonded to the N-terminal are used to synthesize a peptide wherein a carbonyl group of the C-terminal amino acid of C(Mmt)A and an amino group of an N-terminal amino acid bonded to the N-terminal of the cancer antigen peptide B are bonded.

The “cancer antigen peptide B” is as defined for the aforementioned “cancer antigen peptide B”. “Fmoc” is a 9-fluorenylmethoxycarbonyl group. “Mmt” is a monomethoxytrityl group. “SBn” is a thiobenzyl group.

In step (2) of the present invention, the peptide obtained in the step (1) and cancer antigen peptide A wherein one cysteine residue protected by Spy group is bonded to the N-terminal are used to synthesize a peptide wherein a thioether group of the cysteine residue bonded to the N-terminal of the cancer antigen peptide B in the peptide obtained in the step (1) and a thioether group of the cysteine residue bonded to the N-terminal of cancer antigen peptide A are bonded.

The “cancer antigen peptide A” is as defined for the aforementioned “cancer antigen peptide A”. “Spy” is a 2-pyridylsulfide group.

In step (3) of the present invention, the peptide obtained in the step (2) and cancer antigen peptide E wherein one cysteine residue protected by Spy group is bonded to the C-terminal are used to synthesize a peptide wherein a thioether group of the cysteine residue bonded to the N-terminal of the cancer antigen peptide A in the peptide obtained in the step (2) and a thioether group of the cysteine residue bonded to the C-terminal of the cancer antigen peptide E are bonded.

The “cancer antigen peptide E” is as defined for the aforementioned “cancer antigen peptide E”.

The compound and peptide of the present invention, and peptides to be intermediates therefor can be produced according to the method described in the Examples of the present specification or a method to be generally used for the peptide synthesis. Examples of the production method include the methods described in the documents such as Peptide Synthesis, Interscience, New York, 1966; The Proteins, Vol. 2, Academic Press Inc., New York, 1976; peptide synthesis, Maruzen Co., LTD., 1975; Basics and Experiment of Peptide Synthesis, Maruzen Co., LTD., 1985; and Development of Pharmaceutical Product subsequent vol. 14, Peptide Synthesis, Hirokawa Shoten, 1991).

Examples of the production method include a method using a solid phase synthesizer by Fmoc method or Boc method, and a method by sequential condensation of Boc-amino acid or Z-amino acid by liquid phase synthesis process (Fmoc is a 9-fluorenylmethoxycarbonyl group, Boc is a t-butoxycarbonyl group, and Z is a benzyloxycarbonyl group).

In the intermediate for the production of the compound of the present invention, a functional group such as an amino group, a carboxy group, and a mercapto group can be protected by a suitable protecting group or deprotected as necessary using protection and deprotection techniques. Preferable protecting groups, protection method, and deprotection method are described in detail, for example, in “Protective Groups in Organic Synthesis 2nd Edition (John Wiley & Sons, Inc.; 1990)”. Examples of the mercapto-protecting group include an acetamidomethyl group and a trityl group.

When the compound of the present invention has a disulfide bond, the disulfide bond can be formed between two different peptides each containing a cysteine residue or between a peptide containing a cysteine residue and cysteine according to a method generally used for peptide chemistry. Examples of the formation method of the disulfide bond include the methods described in the documents such as Peptide Synthesis, Interscience, New York, 1966; The Proteins, Vol. 2, Academic Press Inc., New York, 1976; peptide synthesis, Maruzen Co., LTD., 1975; Basics and Experiment of peptide synthesis, Maruzen Co., LTD., 1985; and Development of Pharmaceutical Product sequential vol. 14, Peptide Synthesis, Hirokawa Shoten, 1991).

Specifically, when a peptide contains one cysteine residue, a compound having a disulfide bond (disulfide compound) can be produced by removing all protecting groups including the mercapto-protecting group on the cysteine side chain and oxidizing the peptide in an inert solvent. In addition, a disulfide compound can be produced by mixing two intermediates having a mercapto group in a suitable solvent and oxidizing the mixture. The method for the oxidation may be selected as appropriate from known methods for disulfide bond formation in usual peptide synthesis. For example, iodine oxidation, a method using air oxidation reaction under alkali conditions, and a method for forming a disulfide bond by adding an oxidant under alkaline or acidic conditions can be mentioned. Here, examples of the oxidant include iodine, dimethyl sulfoxide (DMSO), and potassium ferricyanide. Examples of the solvent include water, acetic acid, methanol, chloroform, DMF, and DMSO, or a mixture thereof. The oxidation reaction often affords a mixture of symmetric and asymmetric disulfide compounds. A desired asymmetric disulfide compound can be obtained by purification using techniques such as various types of chromatography and recrystallization. Alternatively, a selective disulfide bond may be formed by mixing an intermediate having an activated mercapto group and another intermediate having a mercapto group. Examples of the intermediate having an activated mercapto group include a mercapto group bonded with an Npys group (3-nitro-2-pyridinesulphenyl group). Alternatively, one intermediate is mixed with an agent to activate the mercapto group, for example, 2,2′-dithiobis(5-nitropyridine), and then the other intermediate is added thereto, whereby a selective disulfide bond can be formed (Tetrahedron Letters. Vol. 37. No. 9, pp. 1347-1350).

Also, when two or more cysteine residues are contained in the peptide, a method similar to the aforementioned method can be used. In this case, an isomer with a different manner of disulfide bond is obtained. A dimer wherein a disulfide bond is formed between desired cysteine residues can be obtained by using a particular combination of the cysteine side chain-protecting groups. Examples of the combination of protecting groups include MeBzl (methylbenzyl) group and Acm (acetamidomethyl) group, Trt (trityl) group and Acm group, Npys (3-nitro-2-pyridylthio) group and Acm group, and S-Bu-t (S-tert-butyl) group and Acm group. For example, in the case of a combination of MeBzl group and Acm group, a method of forming disulfide bonds between cysteine residues may comprise the steps of removing MeBzl groups and protecting groups other than those of cysteine side chain, subjecting a solution containing the peptide monomers to air oxidation reaction to form a disulfide bond between the deprotected cysteine residues, and then performing deprotection with iodine and oxidation to form a disulfide bond between the cysteine residues protected with Acm groups.

The obtained compound, peptide and intermediate of the present invention can be purified according to a method known to those of ordinary skill in the art and a method generally used for peptide chemistry. For example, they can be purified by techniques such as various types of chromatography (e.g., silica gel column chromatography, ion exchange column chromatography, gel filtration or reversed-phase chromatography) and recrystallization. For example, the recrystallization solvent may be alcohol solvents such as methanol, ethanol, and 2-propanol, ether solvents such as diethyl ether, ester solvents such as ethyl acetate, aromatic hydrocarbon solvents such as benzene and toluene, ketone solvents such as acetone, hydrocarbon solvents such as hexane, aprotonic solvents such as dimethylformamide and acetonitrile, water, or a mixed solvent thereof. Different purification methods described in Jikken Kagaku Kouza (The Chemical Society of Japan ed., Maruzen) vol. 1 or other documents also may be used.

Purification methods for disulfide compounds are described in the documents such as Peptide Synthesis, Interscience, New York, 1966; The Proteins, Vol. 2, Academic Press Inc., New York, 1976; peptide synthesis, Maruzen Co., LTD., 1975; Basics and Experiment of Peptide Synthesis, Maruzen Co., LTD., 1985; and Development of Pharmaceutical Product sequential vol. 14. peptide synthesis, Hirokawa Shoten, 1991. Among these, HPLC is preferable.

When the compound of the present invention has one or more asymmetric points, the compound can be produced according to a general method and using a starting material (amino acid) having the asymmetric points. To increase the optical purity of the compound of the present invention, processes such as optical resolution may be performed at a suitable stage of the production step. Examples of the optical resolution method include a diastereomer method that forms a salt of the compound of the present invention or an intermediate thereof with an optically active acid (e.g., monocarboxylic acids such as mandelic acid, N-benzyloxyalanine, and lactic acid, dicarboxylic acids such as tartaric acid, o-diisopropylidenetartaric acid, and malic acid, or sulfonic acids such as camphorsulfonic acid and bromocamphorsulfonic acid) in an inert solvent (e.g., alcohol solvents such as methanol, ethanol, and 2-propanol, ether solvents such as diethyl ether, ester solvents such as ethyl acetate, hydrocarbon solvents such as toluene, aprotonic solvents such as acetonitrile, or a mixed solvent thereof). When the compound of the present invention or intermediate has an acidic functional group such as carboxy group, optical resolution can also be performed by forming a salt with an optically active amine (e.g., organic amine such as α-phenethylamine, kinin, quinidine, cinchonidine, cinchonine, and strychnine).

The temperature for forming a salt is selected from the range of room temperature to the boiling point of the solvent. To improve the optical purity, it is desirable to once raise the temperature to around the boiling point of the solvent. When the precipitated salt is collected by filtration, it can be cooled as necessary to increase the yield. A suitable amount of the optically active acid or amine to be used is within the range of about 0.5-about 2.0 equivalents, preferably about 1 equivalent, relative to the substrate. Where necessary, the crystals may be recrystallized in an inert solvent (e.g., alcohol solvents such as methanol, ethanol, and 2-propanol, ether solvents such as diethyl ether, ester solvents such as ethyl acetate, hydrocarbon solvents such as toluene, aprotonic solvents such as acetonitrile, or a mixed solvent thereof) to afford an optically active salt with high purity. Where necessary, an optically resolved salt may be treated with an acid or base by a general method to give a free form.

Examples of the “pharmaceutically acceptable salt” in the present invention include acid addition salt and base addition salt. Examples of the acid addition salt include inorganic acid salts such as hydrochloride, hydrobromide, sulfate, hydroiodide, nitrate, and phosphate, and organic acid salts such as citrate, oxalate, acetate, formate, propionate, benzoate, trifluoroacetate, maleate, tartrate, methanesulfonate, benzenesulfonate, and p-toluenesulfonate. Examples of the base addition salt include salts with inorganic base such as sodium salt, potassium salt, calcium salt, magnesium salt, and ammonium salt, salts with organic base such as triethylammonium salt, triethanolammonium salt, pyridinium salt, and diisopropylammonium salt, and furthermore, amino acid salts of basic or acidic amino acids such as arginine, aspartic acid, and glutamic acid.

The present invention also encompasses hydrates, solvates such as ethanol solvate of the compound of the present invention or a pharmaceutically acceptable salt thereof. Furthermore, the present invention encompasses any stereoisomers that can be present such as any diastereomer and enantiomer, and any crystals in any forms, of the compound represented by the formula (1).

In general, in the production of peptides, various byproducts such as peptides lacking amino acid residues, peptides degraded by hydrolysis, oxidation, or other reactions, and peptides with racemized amino acid residues occur in the steps such as a step of condensing an optically active α-amino acid, a step of removing various protecting groups, and a step of cleaving a peptide from a resin. At a laboratory scale, various types of chromatography (e.g., silica gel column chromatography, ion exchange column chromatography, gel filtration, and reversed-phase chromatography) are combined to remove such impurities, whereby a peptide or compound with high purity can be obtained. However, it is not easy to obtain a peptide or compound with high purity at an industrial scale to provide pharmaceutical products.

The compound of the present invention has physicochemical properties to allow mass production of a drug substance for pharmaceutical products. Specifically, the compound of the present invention has properties such as high solubility and superior stability in a solution and it does not easily turn into a gel when concentrated, and the compound can be produced easily as a drug substance with high purity in a purification step using column chromatography such as reversed-phase HPLC even at a large scale.

The compound of the present invention thus produced is superior in stability against agents such as oxidant in a solution because the cysteine residues form a disulfide bond, for example, and retains a given quality as a drug substance of medicaments and an efficient CTL induction activity.

The compound of the present invention is useful as an active ingredient of a composition for inducing CTLs for cancer immunotherapy, an active ingredient of a cancer vaccine, or an active ingredient of a pharmaceutical composition. That is, the compound of the present invention has, as shown in the Examples of the present specification, superior immunogenicity and can efficiently show a superior CTL induction activity. In addition, CTLs induced by the compound of the present invention can surprisingly recognize a naturally-occurring partial peptide of a cancer antigen protein inherently present in cancer cells.

The CTL induction activity can be detected by measuring the number of CTLs by the HLA tetramer method (Int. J. Cancer: 100, 565-570 (2002)) or limiting dilution method (Nat. Med.: 4, 321-327 (1998)). Alternatively, HLA-A24-restricted CTL induction activity can be examined by using the HLA-A24 model mouse described in WO 02/47474 and Int. J. Cancer: 100, 565-570 (2002), for example.

Therefore, the compound of the present invention can be used as a therapeutic drug or prophylactic drug (recurrence preventive drug) for cancer expressing a cancer antigen protein or cancer associated with an increased level of gene expression of a cancer antigen protein. Examples of the cancer include hematologic cancer such as leukemia, myelodysplastic syndrome, multiple myeloma, and malignant lymphoma, and solid tumor such as gastric cancer, colorectal cancer, lung cancer, breast cancer, germ cell cancer, liver cancer, skin cancer, urinary bladder cancer, prostate cancer, uterine cancer, cervical cancer, ovarian cancer, and brain tumor.

The compound of the present invention or a pharmaceutically acceptable salt thereof can be an active ingredient of a composition of inducing CTLs for cellular immunotherapy of cancer, an active ingredient of a cancer vaccine or/and an active ingredient of a pharmaceutical composition, in a form suitable for each compound or salt.

The compound of the present invention can be administered together with a carrier acceptable as a medicament such as a suitable adjuvant so that its cellular immunity will be established effectively. Adjuvants such as those described in a document (Clin. Microbiol. Rev., 7: 277-289, 1994) may be applicable. Specifically, fungus-derived components, GM-CSF, cytokines such as interleukin-2, interleukin-7, and interleukin-12, plant-derived components, marine organism-derived components, mineral gel such as aluminum hydroxide, lysolecithin, surfactants such as pluronic polyol, polyanion, peptide, and oil emulsion (emulsion preparation) may be mentioned. Examples of the fungus-derived components include lipid A, monophosphoryl lipid A, which is a derivative of lipid A, dead bacteria (Mycobacterium bacteria such as BCG bacteria), bacterium-derived proteins, polynucleotides, Freund's Incomplete Adjuvant, Freund's Complete Adjuvant, cell wall skeleton components (e.g., BCG-CWS), trehalose dimycolate (TDM).

In addition, the compound of the present invention also can be administered in the form of a liposome preparation, a particulate preparation comprising the compound bound to a bead with a diameter of several μm, or a preparation comprising the compound bound to a lipid, for example.

Furthermore, the compound of the present invention (conjugate) can be administered together with an MHC class II-restricted peptide (namely, helper peptide). While the conjugate and a helper peptide may be individually administered, a cocktail preparation (also called as cocktail composition or cocktail) containing the conjugate and a helper peptide in a single pharmaceutical composition is more preferable. The cocktail preparation contains an MHC class II-restricted peptide (namely, helper peptide) in addition to a conjugate capable of producing an MHC class I-restricted peptide (i.e., killer peptide). Therefore, when administered as a cancer vaccine for cancer immunotherapy, the cocktail preparation containing a helper peptide can also activate helper T cells, which are important for functional promotion of other T cells including CTLs, and improve function and efficacy of the conjugate such as cellular immunogenicity.

The MHC class II-restricted peptide (namely, helper peptide) is as described herein. The improved efficacy of the cocktail preparation as a cancer vaccine such as cellular immunogenicity have been confirmed as shown in Examples and Experimental Examples, for example.

While the dose of the compound of the present invention in the preparation may be appropriately controlled depending on factors such as the disease to be treated or age and body weight of the patient, it is generally 0.0001 mg-1000 mg, preferably 0.001 mg-1000 mg, more preferably 0.1 mg-10 mg.

Examples of administration methods include intradermal administration, subcutaneous administration, intramuscular administration, intravenous administration, and transdermal administration. Intradermal administration and subcutaneous administration are preferable because they efficiently induce CTLs. While the administration frequency and administration intervals may be appropriately controlled depending on the disease to be prevented or treated and individual difference in patients, the compound is generally administered more than once, and preferably once per several days to several months.

Administration of a pharmaceutical composition comprising the compound of the present invention as described above as an active ingredient to patients positive for a cancer antigen protein achieves prophylaxis or treatment of cancer.

EXAMPLES

The present invention is specifically explained in the following by referring to Examples, to which, however, the invention is not limited.

Example 1

Synthesis of the Peptide Consisting of the Following Amino Acid Sequence:

(SEQ ID NO: 100) CKIFGSLAFL

1. Synthesis of the Protected Peptide Resin Fmoc-Lys(Boc)-Ile-Phe-Gly-Ser(tBu)-Leu-Ala-Phe-Leu-Alko-Resin(SEQ ID NO: 243)

8.25 g of Fmoc-Leu-Alko-resin (Alko is p-alkoxybenzylalcohol) (manufactured by Watanabe Chemical; 0.77 mmol/g) was placed in a 1.0 L glass reaction vessel and treated with 150 mL of 30% Pip (piperidine)/DMF (dimethylformamide) solution (10 min×1, 5 min×2: a total of 450 mL) to remove Fmoc group (step 1). After washing of the resin with DMF and diethyl ether, 6.2 g (5 equivalents) of Fmoc-Phe-OH, 6.04 g (5 equivalents) of HBTU (O-benzotriazol-1-yl-N,N,N′,N′-tetramethyluronium hexafluorophosphate) and 2.46 g (5 equivalents) of HOBT (1-hydroxybenzotriazole) were added, subsequently 150 ml of DMF and 5.52 ml (5 equivalents) of DIEA (N,N-diisopropylethylamine) were added, and the mixture was stirred at room temperature for 3 hr (step 2). The resin was washed with DMF twice to synthesize Fmoc-Phe-Leu-Alko resin.

Step 1 and step 2 were sequentially performed by using each of the amino acids shown below.

5.14 g of Fmoc-Ala-OH, 5.69 g of Fmoc-Leu-OH, 6.18 g of Fmoc-Ser(tBu)-OH, 4.97 g of Fmoc-Gly-OH, 6.63 g of Fmoc-Phe-OH, 5.98 g of Fmoc-Ile-OH, and 7.83 g of Fmoc-Lys (Boc)-OH.

For Fmoc-Ser(tBu)-OH, step 2 was repetitively performed three times. After washing of the obtained resin with DMF, an unreacted amino group was capped using 25% Ac₂O (acetic anhydride) (15 min×2). Finally, washing with DMF was carried out to give 14.14 g of Fmoc-Lys(Boc)-Ile-Phe-Gly-Ser(tBu)-Leu-Ala-Phe-Leu-Alko-Resin(SEQ ID NO: 243).

2. Synthesis of the Protected Peptide Resin H-Cys(tBu)-Lys(Boc)-Ile-Phe-Gly-Ser(tBu)-Leu-Ala-Phe-Leu-Alko-Resin(SEQ ID NO: 244)

503 mg of the protected peptide resin Fmoc-Lys(Boc)-Ile-Phe-Gly-Ser(tBu)-Leu-Ala-Phe-Leu-Alko-Resin(SEQ ID NO: 243) obtained by the aforementioned operation was placed in a 25 ml glass reaction vessel, and subjected to the deprotection operation of step 1 while being shaken in a rotary shaker N-500 manufactured by Kokusan Chemical, to give H-Lys(Boc)-Ile-Phe-Gly-Ser(tBu)-Leu-Ala-Phe-Leu-Alko-Resin(SEQ ID NO: 245). A solution of 340.4 mg of Fmoc-Cys(tBu)-OH, 248.2 mg of HBTU and 92.9 mg of HOBT dissolved in 10 ml of DMF was added, further 0.2 ml of DIEA was added, and the mixture was shaken at room temperature for 3 hr, whereby the coupling reaction of step 2 was performed. After washing with 10 ml of DMF 4 times, Fmoc group was cleaved by treatment with 30% Pip/DMF 10 ml (10 min×1 and 5 min×2). 100 ml of TFA cocktail (2.5% tetraisopropylsilane/2.5% dodecanethiol/2.5% H₂O/92.5% TFA solution) was added, and the mixture was stirred at room temperature for 2.0 hr. Thereafter, diethyl ether was added, and filtration through a glass filter was performed to remove TFA cocktail and diethyl ether as a filtrate. The residue was washed with diethyl ether to give 269.5 mg of crude peptide (CKIFGSLAFL (SEQ ID NO: 100)).

3. Purification of the Crude Peptide

The obtained crude peptide (269.5 mg) was charged into HPLC (manufactured by Shimadzu; LC8AD) loaded with a Daiso-Pak ODS 30 I.D.×250 mm column (manufactured by Daiso) equilibrated with eluting solution 1 (H₂O/0.1% TFA) and eluting solution 2 (CH₃CN/0.1% TFA) with the concentration of eluting solution 2 (CH₃CN/0.1% TFA) set to 24.3%. While monitoring the eluate of the peptide of interest by 220 nm UV, the concentration of eluting solution 2 was raised to 44.3% in 80 min, and the fractions containing the peptide of interest were collected. The obtained solution was freeze dried to give 49 mg of the desired purified product.

pump: manufactured by Shimadzu; LC-8A column: ODS Daiso-Pak ODS 30 I.D. cmϕ×cmL eluting solution 1: H₂O/0.1% TFA eluting solution 2: CH₃CN/0.1% TFA flow rate: 20 ml/min column temperature: 40° C. detection: UV 220 nm mass spectrometry: LC-ESI/MS m/z=1098.9 [M+1]

(Calculated=1098.4) Examples 2-20

By a method similar to that in Example 1, respective peptides consisting of the amino acid sequences of SEQ ID NOs: 95-97 and 108-123 were synthesized. Tables 16 and 17 show the result of mass spectrometry of each synthesized peptide.

All of the peptides in Tables 16 and 17 are the compounds of the present invention of the formula (1) wherein R¹ is a hydrogen atom, X^(a) is a single bond, Y^(a) is a divalent peptide group consisting of 1 amino acid residue, and cancer antigen peptide A is HER2/neu₃₆₉₋₃₇₇ peptide (KIFGSLAFL) (SEQ ID NO: 53), which is a partial peptide of the cancer antigen protein HER2/neu.

TABLE 16 amino SEQ mass  mass Ex. acid ID spectrometry: spectrometry: No. sequence NO: LC-ESI/MS m/z Calculated  2 CAKIFGSLAFL  95 1169.8 1169.4 [M + 1]⁺  3 CRKIFGSLAFL 108  628.3 1254.5 [M + 2H]²⁺  4 CNKIFGSLAFL 109 1212.9 1212.5 [M + 1]⁺  5 CDKIFGSLAFL 110 1214.0 1213.4 [M + 1]⁺  6 CCKIFGSLAFL 111 1201.9 1201.5 [M + 1]⁺  7 CQKIFGSLAFL 112 1227.0 1226.5 [M + 1]⁺  8 CGKIFGSLAFL 113 1155.9 1155.4 [M + 1]⁺  9 CHKIFGSLAFL 114  618.8 1235.5 [M + 2H]²⁺ 10 CEKIFGSLAFL 115 1228.0 1227.5 [M + 1]⁺

TABLE 17 amino SEQ mass  mass Ex. acid ID spectrometry: spectrometry: No. sequence NO: LC-ESI/MS m/z Calculated 11 CLKIFGSLAFL  96 1212.0 1211.5 [M + 1]⁺ 12 CMKIFGSLAFL  97 1223.0 1229.6 [M + 1]⁺ 13 CIKIFGSLAFL 116 1212.0 1211.5 [M + 1]⁺ 14 CFKIFGSLAFL 117 1246.0 1245.5 [M + 1]⁺ 15 CPKIFGSLAFL 118 1196.0 1195.5 [M + 1]⁺ 16 CSKIFGSLAFL 119 1186.0 1185.4 [M + 1]⁺ 17 CTKIFGSLAFL 120 1199.9 1199.5 [M + 1]⁺ 18 CWKIFGSLAFL 121 1285.0 1284.6 [M + 1]⁺ 19 CYKIFGSLAFL 122 1261.9 1261.5 [M + 1]⁺ 20 CVKIFGSLAFL 123 1198.0 1197.5 [M + 1]⁺

Reference Example 1

By a method similar to that in Example 1, a peptide consisting of the amino acid sequence of SEQ ID NO: 86 was synthesized. Table 18 shows the result of mass spectrometry of the synthesized peptide.

The peptide of SEQ ID NO: 86 is not the compound of the present invention as mentioned above and is therefore described as Reference Example 1.

TABLE 18 Ref. amino SEQ mass  mass Ex. acid ID spectrometry: spectrometry: No. sequence NO: LC-ESI/MS m/z Calculated 1 CKKIFGSLAFL 86 614.4 1226.5 [M + 2H]²⁺

Examples 21-24

By a method similar to that in Example 1, respective peptides consisting of the amino acid sequences of SEQ ID Nos: 92-94 and 99 were synthesized. Table 19 shows the result of mass spectrometry of each synthesized peptide.

All of the peptides in Table 19 are the compounds of the present invention of the formula (1) wherein R¹ is a hydrogen atom, X^(a) is a single bond, Y^(a) is a single bond or a divalent peptide group consisting of 1 amino acid residue, and cancer antigen peptide A is Proteinase-3₁₆₉₋₁₇₇ peptide (VLQELNVTV) (SEQ ID NO: 43), which is a partial peptide of the cancer antigen protein Proteinase-3.

TABLE 19 mass  amino SEQ spectrometry: mass Ex. acid ID LC-ESI/MS m/z spectrometry: No. sequence NO: [M + 1]⁺ Calculated 21 CVLQELNVTV 99 1117.9 1118.3 22 CAVLQELNVTV 92 1189.0 1189.4 23 CLVLQELNVTV 93 1231.0 1231.5 24 CMVLQELNVTV 94 1249.0 1249.5

Examples 25-28

By a method similar to that in Example 1, respective peptides consisting of the amino acid sequences of SEQ ID NOs: 98, 89-91 were synthesized. Table 20 shows the result of mass spectrometry of each synthesized peptide.

All of the peptides in Table 20 are the compounds of the present invention of the formula (1) wherein R¹ is a hydrogen atom, X^(a) is a single bond, Y^(a) is a single bond or a divalent peptide group consisting of 1 amino acid residue, and cancer antigen peptide A is MAGE-A10₂₅₄₋₂₆₂ peptide (GLYDGMEHL) (SEQ ID NO: 19), which is a partial peptide of the cancer antigen protein MAGE-A10.

TABLE 20 amino SEQ mass  mass Ex. acid ID spectrometry: spectrometry: No. sequence NO: LC-ESI/MS m/z Calculated 25 CGLYDGMEHL 98 569.5 1137.3 [M + 2H]²⁺ 26 CAGLYDGMEHL 89 1209.0 1208.5 [M + 1]⁺ 27 CLGLYDGMEHL 90 1250.9 1250.5 [M + 1]⁺ 28 CMGLYDGMEHL 91 1269.0 1268.5 [M + 1]⁺

Experimental Example 1

Test of trimming of N-terminal amino acid by ERAP1 The peptides synthesized in Examples 1-20 were evaluated for N-terminal amino acid trimming efficiency using ERAP1 (PLoS One November 2008, vol. 3, Issue 11, e3658). 50 μl of ERAP1 solution (50 ng/ml) in pH 8.0, 20 mM Tris.HCl-100 mM NaCl buffer (Tris.HCl buffer) was added to 142 μl of Tris.HCl buffer. An aqueous solution of 2.5 mM each peptide (8.0 μl) was added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at room temperature. 1.0 hr later, 50 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide [HER2/neu₃₆₉₋₃₇₇ peptide (KIFGSLAFL) (SEQ ID NO: 53)] obtained by trimming was determined based on the obtained AUC, and is shown in Table 21.

analysis conditions pump: UFLC manufactured by Shimadzu column: Shim-pack XR-ODS 3.0 mmi.d.×75 mm solution: 0.05% TFA H₂O(A)-0.05% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: concentration of SOLUTION B was raised from 10% to 60% from 0.0 min to 5.0 min

TABLE 21 formation rate of SEQ KIFGSLAFL Exam- ID (SEQ ID NO: ple amino acid sequence NO: 53) (%)  1 CKIFGSLAFL 100 27.6  2 CAKIFGSLAFL  95 49.7  3 CRKIFGSLAFL 108 5.7  4 CNKIFGSLAFL 109 0  5 CDKIFGSLAFL 110 0  6 CCKIFGSLAFL 111 2.1  7 CQKIFGSLAFL 112 69.4  8 CGKIFGSLAFL 113 0  9 CHKIFGSLAFL 114 5.6 10 CEKIFGSLAFL 115 20.3 11 CLKIFGSLAFL  96 13.5 12 CMKIFGSLAFL  97 26.7 13 CIKIFGSLAFL 116 31.7 14 CFKIFGSLAFL 117 13.4 15 CPKIFGSLAFL 118 0 16 CSKIFGSLAFL 119 51.2 17 CTKIFGSLAFL 120 13.1 18 CWKIFGSLAFL 121 3.92 19 CYKIFGSLAFL 122 5.3 20 CVKIFGSLAFL 123 36.6

Experimental Example 2 Time-Course Changes of Trimming of N-Terminal Amino Acid by ERAP1.

The peptides synthesized in Examples 1-2, 11-12, and 21-28 were evaluated for time-course changes of the trimming of the N-terminal amino acid(s) by ERAP1. 20 μl of ERAP1 solution (0.5 mg/ml) in Tris.HCl buffer was added to 172 μl of Tris.HCl buffer. 10 mM peptide solution in DMSO (8.0 μl) was added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at room temperature. 1.0, 2.0, 4.0, and 8.0 hr later, 50 μl of the sample was added to 150 μl of MeOH to terminate the reaction, 25 μl of the resulting solution was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide obtained by trimming was determined based on the obtained AUC, and is shown in Table 22.

analysis conditions pump: UFLC manufactured by Shimadzu column: Shim-pack XR-ODS 3.0 mmi.d.×75 mm solution: 0.05% TFA H₂O(A)-0.05% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: A=220 nm gradient: Concentration of SOLUTION B was raised from 1.0% to 70% from 0.0 min to 5.0 min peptide of interest:

The peptide to be obtained by the trimming of the N-terminal amino acid(s) by ERAP1 is,

in the case of each peptide of SEQ ID NOs: 100 and 95-97, HER2/neu₃₆₉₋₃₇₇ peptide (KIFGSLAFL) (SEQ ID NO: 53), in the case of each peptide of SEQ ID NOs: 99 and 92-94, Proteinase-3₁₆₉₋₁₇₇ peptide (VLQELNVTV) (SEQ ID NO: 43), or in the case of peptide of SEQ ID NOs: 98 and 89-91, MAGE-A10₂₅₄₋₂₆₂ peptide (GLYDGMEHL) (SEQ ID NO: 19).

TABLE 22 formation rate (%) Ex. No. SEQ ID NO: 1 hr later 2 hr later 4 hr later 8 hr later 1 100 20.0 30.7 33.9 22.0 2 95 17.0 35.5 44.3 23.0 11 96 6.9 11.3 16.0 13.3 12 97 10.5 13.4 24.1 20.9 21 99 83.4 85.6 78.8 83.9 22 92 46.1 49.9 51.3 53.5 23 93 31.1 36.9 38.1 36.1 24 94 28.7 34.5 36.5 36.8 25 98 95.1 106 100 101 26 89 87.8 99.4 103 97.5 27 90 58.3 94.9 88.4 88.3 28 91 90.6 103 96.0 101

Experimental Example 3 Evaluation of In Vivo CTL Induction Ability Using HIA-A0201 Transgenic Mouse

The CTL induction ability of each peptide extended by cysteine (Cys) (Cys-extended peptide) shown in Table 23 was evaluated by in vivo CTL induction test using an HLA-A0201 transgenic mouse.

TABLE 23 SEQ Exam- ID ple amino acid sequence NO:  1 CKIFGSLAFL 100 21 CVLQELNVTV  99 25 CGLYDGMEHL  98

HLA-A0201 transgenic mouse (C57BL/6CrHLA-A2.1DR1) is a mouse which is defective in mouse MHC, and expresses a chimera HLA of human MHC HLA-A0201 and mouse MHC H-2D^(b), and HLA-DRB1*0101. Using this mouse, peptides capable of inducing CTLS in HLA-A02 positive humans can be selected (Eur J Immunol. 2004; 34: 3060-9).

Whether the administration of the peptide extended by Cys (SEQ ID NO: 100, 99 or 98) results in the induction of CTLs to a peptide (SEQ ID NO: 53, 43 or 19) endogenously presented by cancer cells was determined based on the measurement of IFNγ production by re-stimulation, with the peptide (SEQ ID NO: 53, 43 or 19), of the splenocyte derived from the above-mentioned mouse administered with the peptide extended by Cys (SEQ ID NO: 100, 99 or 98). The peptide (SEQ ID NO: 53, 43 or 19) endogenously presented by cancer cells shown in Table 24 is also referred to as a Cys non-extended peptide in this Experimental Example.

TABLE 24 SEQ amino acid sequence ID NO: KIFGSLAFL 53 VLQELNVTV 43 GLYDGMEHL 19

Specifically, each peptide (SEQ ID NO: 19, 43, 53, 98, 99 or 100) was dissolved in dimethyl sulfoxide (DMSO) at 200 mg/mL, further diluted with phosphate buffered saline (PBS, pH 5) to 2 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified peptide was intradermally administered to 2 sites at the base of tail of the mouse at 50 μg/site. One week later, the mouse was euthanized with CO₂, gas, the spleen was isolated, and splenocytes were prepared. IFNγ ELISPOT assay kit was used for the measurement of IFNγ production. On the previous day of splenocyte preparation, an ELISPOT plate was treated with an anti-mouse IFNγ antibody, and blocked with RPMI1640 medium containing 10% FBS the next day. The prepared HLA-A0201 transgenic mouse-derived splenocytes were plated at 2.5×10⁵ cells/well on the blocked ELISPOT plate. Each peptide (SEQ ID NO: 19, 43, 53, 98, 99 or 100) was dissolved in DMSO at 40 mg/mL, and further diluted with RPMI1640 medium containing 10% FBS to 40 μg/mL. The splenocytes derived from the mouse administered with the peptide represented by SEQ ID NO: 53 or 100 were pulsed with each of the diluted peptides represented by SEQ ID NO: 53 and 100 (final concentration: 10 μg/mL). The splenocytes derived from the mouse administered with the peptide represented by SEQ ID NO: 43 or 99 were pulsed with each of the diluted peptides represented by SEQ ID NOs: 43 and 99 (final concentration: 10 μg/mL). The splenocytes derived from the mouse administered with the peptide represented by SEQ ID NO: 19 or 98 were pulsed with each of the diluted peptides represented by SEQ ID NOs: 19 and 98 (final concentration: 10 μg/mL). These splenocytes were cultivated for 20 hr at 37° C., 5% CO₂, whereby peptide re-stimulation in vitro was performed. Thereafter, the supernatant was removed, and the ELISPOT plate was allowed to develop color according to the attached protocol. The number of spots that developed color was measured by KS ELISPOT.

The results of IFNγ ELISPOT assay are shown in FIGS. 5-7. In each Figure, the vertical axis shows the number of cells that responded among the plated cells. In any of Figures, the value of the white bar showing the result in the non-pulsed state is hardly detected. This means that the splenocytes of respective transgenic mice did not react at all in the absence of peptide re-stimulation. That is, the difference in the values of the color bar and the white bar shows the number of CTLs specific to the peptide used in in vitro re-stimulation, and that CTLs were induced in the mouse in vivo by the administration of each peptide. Here, the color bar means the black bar showing the result in the pulsed state with the Cys non-extended peptide, or the gray bar showing the result in the pulsed state with the Cys-extended peptide. FIG. 5 shows the results of administration of the peptide represented by SEQ ID NO: 53 or 100. FIG. 6 shows the results of administration of the peptide represented by SEQ ID NO: 43 or 99. FIG. 7 shows the results of administration of the peptide represented by SEQ ID NO: 19 or 98. From the above, a similar level of IFNγ production was confirmed by in vitro stimulation with the Cys non-extended peptide or the Cys-extended peptide in the HLA-A0201 transgenic mouse-derived splenocytes, regardless of the presence or absence of Cys extension of the peptide administered in vivo, and it was demonstrated that the Cys-extended peptide (SEQ ID NO: 100, 99 and 98) has an in vivo CTL induction ability. That is, it was demonstrated that the administration of the Cys-extended peptide (SEQ ID NO: 100, 99 or 98) can induce CTLs that can recognize the Cys non-extended peptide (SEQ ID NO: 53, 43 or 19). This means that the Cys-extended peptide can induce CTLs recognizing a peptide (Cys non-extended peptide) endogenously presented by cancer cells. It was strongly suggested that the Cys-extended peptide undergoes appropriate trimming by ERAP1 in mice in vivo and is indeed processed into the Cys non-extended peptide.

Example 29

Synthesis of the Compound Represented by the Formula (4)

wherein the bond between C and C is a disulfide bond

step 1. (SEQ ID NO: 246) Synthesis of H-Cys(Pys)-Gly-Leu-Tyr-Asp-Gly-Met- Glu-His-Leu-OH) 

[i.e., Synthesis of the Compound Represented by the Formula (13):

1.20 mL of an isopropanol solution of 2,2′-bispyridyl disulfide (0.2 M) was added to 2.74 mL of 20% (w/w) acetic acid aqueous solution of H-Cys-Gly-Leu-Tyr-Asp-Gly-Met-Glu-His-Leu-OH (SEQ ID NO: 98) (274 mg) obtained in Example 25, and the mixture was stirred at room temperature for 30 min. The reaction mixture was purified by reversed-phase HPLC. pump: manufactured by Shimadzu; LC-8A

column: YMC ODS-A 3 cmϕ×25 cmL, 10 μm eluting solution 1: H₂O/0.1% TFA eluting solution 2: CH₃CN/0.1% TFA flow rate: 20 ml/min detection: UV 220 nm

The reaction solution was injected to a column equilibrated with 10% eluting solution 2. Thereafter, the concentration of eluting solution 2 was raised to 32% over 10 min and then raised at a rate of 0.25% per minute. Fractions containing the desired product were collected and freeze dried to give 230 mg of H-Cys(Pys)-Gly-Leu-Tyr-Asp-Gly-Met-Glu-His-Leu-OH(SEQ ID NO: 246) (i.e., the compound represented by the formula (13)).

mass spectrometry: LC-ESI/MS m/z=1246.7 [M+H]¹⁺ (Calculated=1246.5)

step 2. Synthesis of (H-Cys-Gly-Leu-Tyr-Asp-Gly-Met-Glu- His-Leu-OH) (H-Cys-Lys-Ile-Phe-Gly-Ser-Leu-Ala-Phe-Leu-OH) disulfide bond

[i.e., Synthesis of the Compound Represented by the Formula (4):

wherein the bond between C and C is a disulfide bond]

27 mg of H-Cys(Pys)-Gly-Leu-Tyr-Asp-Gly-Met-Glu-His-Leu-OH(SEQ ID NO: 246) (i.e., the compound represented by the formula (13)) obtained in step 1 and 23 mg of H-Cys-Lys-Ile-Phe-Gly-Ser-Leu-Ala-Phe-Leu-OH (SEQ ID NO: 100) obtained in Example 1 were mixed, 2 mL of 20% (v/v) acetic acid aqueous solution was added, and the mixture was stirred at room temperature for 30 min. The reaction mixture was purified by reversed-phase HPLC.

pump: manufactured by Shimadzu; LC-8A column: YMC ODS-A 3 cmϕ×25 cmL, 10 μm eluting solution 1: H₂O/0.1% TFA eluting solution 2: CH₃CN/0.1% TFA flow rate: 20 ml/min detection: UV 220 nm

The reaction solution was injected to a column equilibrated with 10% eluting solution 2. Thereafter, the concentration of eluting solution 2 was raised to 34% over 10 min and then raised at a rate of 0.25% per minute. Fractions containing the desired product were collected and freeze dried to give 21 mg of the desired compound represented by the formula (4).

mass spectrometry: LC-ESI/MS m/z=1118.0 [M+2H]²⁺ (Calculated=1117.8)

Example 30

Synthesis of the Compound Represented by the Formula (10):

wherein the bond between C and C is a disulfide bond

By a method similar to that in Example 29, the compound represented by the formula (10) was synthesized. mass spectrometry: LC-ESI/MS m/z=1082.2 [M+2H]²⁺ (Calculated=1082.3)

Experimental Example 4

Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The compound represented by the formula (4) synthesized in Example 29 was evaluated for the CTL induction ability by an in vivo CTL induction test using an HLA-A0201 transgenic mouse. The compound represented by the formula (4):

wherein the bond between C and C is a disulfide bond, is, in particular, a compound of the aforementioned formula (1) wherein cancer antigen peptide A is GLYDGMEHL (SEQ ID NO: 19) and cancer antigen peptide B is KIFGSLAFL (SEQ ID NO: 53). GLYDGMEHL (SEQ ID NO: 19) and KIFGSLAFL (SEQ ID NO: 53) are HLA-A0201-restricted cancer antigen peptides.

The HLA-A0201 transgenic mouse (C57BL/6CrHLA-A2.1DR1) is a mouse which is defective in mouse MHC, and expresses a chimera HLA of human MHC HLA-A0201 and mouse MHC H-2D^(b), and HLA-DRB1*0101. Using this mouse, peptides capable of inducing CTLs in HLA-A02 positive humans can be selected (Eur J Immunol. 2004; 34: 3060-9).

To evaluate whether CTLs to each of the peptides (SEQ ID NOs: 19 and 53) endogenously presented by cancer cells was induced, the compound represented by the formula (4) was administered to the HLA-A0201 transgenic mouse. That is, it was determined whether IFNγ production was observed by re-stimulation, with the peptide (SEQ ID NO: 19 or 53), of the splenocyte derived from the above-mentioned mouse administered with the compound represented by the formula (4).

Specifically, the compound represented by the formula (4) was diluted with water for injection to 10 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 250 μg/site. One week later, the mouse was euthanized with CO₂ gas, the spleen was isolated, and splenocytes were prepared. IFNγ ELISPOT assay kit was used for the measurement of IFNγ production. On the previous day of splenocyte preparation, an ELISPOT plate was treated with an anti-mouse IFNγ antibody, and blocked with RPMI1640 medium containing 10% FBS the next day. The prepared HLA-A0201 transgenic mouse-derived splenocytes were plated at 0.25×10⁶ cells/well on the blocked ELISPOT plate. Each of the peptide (SEQ ID NOs: 19 and 53) was dissolved in DMSO at 40 mg/mL, and further diluted with RPMI1640 medium containing 10% FBS to 40 μg/mL. The HLA-A0201 transgenic mouse-derived splenocytes were pulsed with the diluted peptide represented by SEQ ID NO: 19 or SEQ ID NO: 53 (final concentration: 10 μg/mL), and cultivated for 20 hr at 37° C., 5% CO₂, whereby peptide re-stimulation in vitro was performed. After the culture, the supernatant was removed, and the ELISPOT plate was allowed to develop color according to the attached protocol. The number of spots that developed color was measured by ImmunoSpot Analyzer (manufactured by C.T.L.).

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIG. 8.

In FIG. 8, the vertical axis shows the number of cells that responded among the plated cells. In FIG. 8, the black bar and the shaded bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes while being pulsed with the peptides shown by SEQ ID NOs: 19 and 53, respectively, and the white bar show the result of culture without pulsing. That is, the difference in the values of the black or shaded bar and the white bar shows the number of peptide-specific CTLs, and that the administration of the compound represented by the formula (4) resulted in the induction of CTLs specific to each of the peptides shown by SEQ ID NOs: 19 and 53 in vivo in the mouse.

In FIG. 8, the value of the white bar is not detected. This means that the splenocytes of the HLA-A0201 transgenic mouse did not react at all in the absence of pulsing with the peptide of interest. As a result of this test, IFNγ production specific to each of the peptides shown by SEQ ID NOs: 19 and 53 was detected in the HLA-A0201 transgenic mouse-derived splenocytes.

From the above, it was demonstrated that the compound represented by the formula (4) can induce CTLs specific to each of the peptides shown by SEQ ID NOs: 19 and 53. It was strongly suggested that the compound represented by the formula (4) undergoes cleavage of disulfide bond and appropriate trimming by ERAP-1 in mice in vivo and is indeed processed into the peptides shown by SEQ ID NOs: 19 and 53.

That is, it was demonstrated that the compound represented by the formula (4), which is one embodiment of the compound of the present invention, is a conjugate wherein two different peptides form a composite via the disulfide bond shown in the formula (1), and is a cancer antigen peptide conjugate vaccine that indeed can induce different two types of CTLs in vivo.

Experimental Example 5 Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse and HLA-A2402 Transgenic Mouse

The compound represented by the formula (10) synthesized in Example 30 was evaluated for the CTL induction ability by an in vivo CTL induction test using an HLA-A0201 transgenic mouse and an HLA-A2402 transgenic mouse. The compound represented by the formula (10):

wherein the bond between C and C is a disulfide bond, is, in particular, a compound of the aforementioned formula (1) wherein cancer antigen peptide A is GLYDGMEHL (SEQ ID NO: 19) and cancer antigen peptide D is VYGFVRACL (SEQ ID NO: 87). GLYDGMEHL (SEQ ID NO: 19) is an HLA-A0201-restricted cancer antigen peptide, and VYGFVRACL (SEQ ID NO: 87) is an HLA-A24-restricted cancer antigen peptide.

The HLA-A0201 transgenic mouse is as described in Experimental Example 4. On the other hand, the HLA-A2402 transgenic mouse (C57BL/6CrHLA-A2402/K^(b)) is a mouse that expresses a chimera HLA of human MHC HLA-A2402 and mouse MHC H-2K^(b). Using this mouse, peptides capable of inducing CTLs in HLA-A24 positive humans can be selected (Int J Cancer. 2002; 100: 565-70).

To evaluate whether CTLs to each of the peptides (SEQ ID NOs: 19 and 87) endogenously presented by cancer cells was induced, the compound represented by the formula (10) was administered to the HLA-A0201 transgenic mouse and the HLA-A2402 transgenic mouse. That is, it was determined whether IFNγ production was observed by re-stimulation, with the peptide (SEQ ID NO: 19 or 87), of the splenocyte derived from the above-mentioned mouse administered with the compound represented by the formula (10).

Specifically, the compound represented by the formula (10) was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 10 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 250 μg/site. One week later, the mouse was euthanized with CO₂ gas, the spleen was isolated, and splenocytes were prepared. IFNγ ELISPOT assay kit was used for the measurement of IFNγ production. On the previous day of splenocyte preparation, an ELISPOT plate was treated with an anti-mouse IFNγ antibody, and blocked with RPMI1640 medium containing 10% FBS the next day. The prepared HLA-A0201 transgenic mouse-derived splenocytes were plated at 0.25×10⁶ cells/well, and HLA-A2402 transgenic mouse-derived splenocytes were plated at 0.5×10⁶ cells/well, on the blocked ELISPOT plate. Each of the peptide (SEQ ID NOs: 19 and 87) was dissolved in DMSO at 40 mg/mL, and further diluted with RPMI1640 medium containing 10% FBS to 40 μg/mL. The HLA-A0201 transgenic mouse-derived splenocytes were pulsed with the diluted peptide represented by SEQ ID NO: 19 (final concentration: 10 μg/mL), and the HLA-A2402 transgenic mouse-derived splenocytes were pulsed with the diluted peptide represented by SEQ ID NO: 87 (final concentration: 10 μg/mL). These splenocytes were cultivated for 20 hr at 37° C., 5% CO₂, whereby peptide re-stimulation in vitro was performed. After the culture, the supernatant was removed, and the ELISPOT plate was allowed to develop color according to the attached protocol. The number of spots that developed color was measured by ImmunoSpot Analyzer (manufactured by C.T.L.).

The results of IFN ELISPOT assay using HLA-A0201 transgenic mouse are shown in FIG. 9, and the results of IFNγ ELISPOT assay using HLA-A2402 transgenic mouse are shown in FIG. 10.

In each Figure, the vertical axis shows the number of cells that responded among the plated cells. In FIG. 9, the black bar and the white bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes while being pulsed and non-pulsed with the peptide represented by SEQ ID NO: 19, respectively, and in FIG. 10, the black bar and the white bar show the results of culture of HLA-A2402 transgenic mouse-derived splenocytes while being pulsed and non-pulsed with the peptide represented by SEQ ID NO: 87, respectively. That is, the difference in the values of the black bar and the white bar shows the number of peptide-specific CTLs, and that the administration of the compound represented by the formula (10) resulted in the induction of CTLs specific to each of the peptides shown by SEQ ID NO: 19 and 87 in vivo in the mouse.

In particular, in FIG. 9, the value of the white bar is not detected. This means that the splenocytes of the HLA-A0201 transgenic mouse did not react at all in the absence of the peptide of interest. As a result of this test, IFNγ production specific to the peptide shown by SEQ ID NO: 19 was detected in the HLA-A0201 transgenic mouse-derived splenocytes, and IFNγ production specific to the peptide shown by SEQ ID NO: 87 was detected in the HLA-A2402 transgenic mouse-derived splenocytes.

From the above, it was demonstrated that the compound represented by the formula (10) can induce CTLs specific to each of the peptide shown by SEQ ID NO: 19 or 87. It was strongly suggested that the compound represented by the formula (10) undergoes cleavage of disulfide bond and appropriate trimming by ERAP-1 in mice in vivo and is indeed processed into the peptides shown by SEQ ID NOs: 19 and 87.

That is, it was demonstrated that the compound represented by the formula (10), which is one embodiment of the compound of the present invention, is a conjugate wherein two different peptides form a composite via the disulfide bond shown in the formula (1), and is a cancer antigen peptide conjugate vaccine that indeed can induce different two types of CTLs in vivo.

Examples 31-49

By a method similar to that in Example 1, respective peptides consisting of the amino acid sequences of SEQ ID NOs: 124-142 were synthesized. Tables 25-26 show the result of mass spectrometry of each synthesized peptide.

All of the peptides in Tables 25 and 26 are the compounds of the present invention of the formula (1) wherein R¹ is a hydrogen atom, X^(a) is a divalent peptide group consisting of 1 amino acid residue, Y^(a) is a single bond, and cancer antigen peptide A is HER2/neu₃₆₉₋₃₇₇ peptide (KIFGSLAFL) (SEQ ID NO: 53), which is a partial peptide of the cancer antigen protein HER2/neu.

TABLE 25 amino SEQ mass  mass Ex. acid ID spectrometry: spectrometry: No. sequence NO: LC-ESI/MS m/z Calculated 31 ACKIFGSLAFL 124 585.6 585.7 [M + 2H]²⁺ 32 RCKIFGSLAFL 125 628.3 628.3 [M + 2H]²⁺ 33 NCKIFGSLAFL 126 607.3 607.2 [M + 2H]²⁺ 34 DCKIFGSLAFL 127 607.9 607.7 [M + 2H]²⁺ 35 QCKIFGSLAFL 128 614.4 614.2 [M + 2H]²⁺ 36 ECKIFGSLAFL 129 614.9 614.7 [M + 2H]²⁺ 37 GCKIFGSLAFL 130 578.8 578.7 [M + 2H]²⁺ 38 HCKIFGSLAFL 131 618.9 618.7 [M + 2H]²⁺ 39 ICKIFGSLAFL 132 606.9 606.8 [M + 2H]²⁺ 40 LCKIFGSLAFL 133 606.8 606.8 [M + 2H]²⁺

TABLE 26 amino SEQ mass  mass Ex. acid ID spectrometry: spectrometry: No. sequence NO: LC-ESI/MS m/z Calculated 41 KCKIFGSLAFL 134 614.4 614.3 [M + 2H]²⁺ 42 MCKIFGSLAFL 135 615.9 615.8 [M + 2H]²⁺ 43 FCKIFGSLAFL 136 623.8 623.8 [M + 2H]²⁺ 44 PCKIFGSLAFL 137 598.8 598.7 [M + 2H]²⁺ 45 SCKIFGSLAFL 138 593.8 593.7 [M + 2H]²⁺ 46 TCKIFGSLAFL 139 600.9 600.7 [M + 2H]²⁺ 47 WCKIFGSLAFL 140 643.4 643.3 [M + 2H]²⁺ 48 YCKIFGSLAFL 141 631.9 631.8 [M + 2H]²⁺ 49 VCKIFGSLAFL 142 599.8 599.7 [M + 2H]²⁺

Examples 50-68

By a method similar to that in Example 1, respective peptides consisting of the amino acid sequences of SEQ ID NOs: 143-161 were synthesized. Tables 27 and 28 show the result of mass spectrometry of each synthesized peptide.

All of the peptides in Tables 27 and 28 are the compounds of the present invention of the formula (1) wherein R¹ is a hydrogen atom, X^(a) is a divalent peptide group consisting of 1 amino acid residue, Y^(a) is a single bond, and cancer antigen peptide A is Proteinase-3₁₆₉₋₁₇₇ peptide (VLQELNVTV) (SEQ ID NO: 43), which is a partial peptide of the cancer antigen protein Proteinase-3.

TABLE 27 amino SEQ mass  mass Ex. acid ID spectrometry: spectrometry: No. sequence NO: LC-ESI/MS m/z Calculated 50 ACVLQELNVTV 143 595.1 595.2 [M + 2H]²⁺ 51 RCVLQELNVTV 144 637.9 637.8 [M + 2H]²⁺ 52 NCVLQELNVTV 145 616.5 616.7 [M + 2H]²⁺ 53 DCVLQELNVTV 146 617.1 617.2 [M + 2H]²⁺ 54 QCVLQELNVTV 147 623.6 623.7 [M + 2H]²⁺ 55 ECVLQELNVTV 148 624.1 624.2 [M + 2H]²⁺ 56 GCVLQELNVTV 149 588.0 588.2 [M + 2H]²⁺ 57 HCVLQELNVTV 150 628.4 628.2 [M + 2H]²⁺ 58 ICVLQELNVTV 151 616.4 616.2 [M + 2H]²⁺ 59 LCVLQELNVTV 152 616.1 616.2 [M + 2H]²⁺

TABLE 28 amino SEQ mass  mass Ex. acid ID spectrometry: spectrometry: No. sequence NO: LC-ESI/MS m/z Calculated 60 KCVLQELNVTV 153 623.8 623.7 [M + 2H]²⁺ 61 MCVLQELNVTV 154 625.2 625.3 [M + 2H]²⁺ 62 FCVLQELNVTV 155 633.3 633.2 [M + 2H]²⁺ 63 PCVLQELNVTV 156 608.0 608.2 [M + 2H]²⁺ 64 SCVLQELNVTV 157 603.0 603.2 [M + 2H]²⁺ 65 TCVLQELNVTV 158 610.1 610.2 [M + 2H]²⁺ 66 WCVLQELNVTV 159 652.8 652.8 [M + 2H]²⁺ 67 YCVLQELNVTV 160 641.3 641.2 [M + 2H]²⁺ 68 VCVLQELNVTV 161 609.3 609.2 [M + 2H]²⁺

Examples 69-84

By a method similar to that in Example 1, respective peptides consisting of the amino acid sequences of SEQ ID NOs: 162-177 were synthesized. Tables 29 and 30 show the result of mass spectrometry of each synthesized peptide.

All of the peptides in Tables 29 and 30 are the compounds of the present invention of the formula (1) wherein R¹ is a hydrogen atom, X^(a) is a single bond, Y^(a) is a divalent peptide group consisting of 1 amino acid residue, and cancer antigen peptide A is MAGE-A10₂₅₄₋₂₆₂ peptide (GLYDGMEHL) (SEQ ID NO: 19), which is a partial peptide of the cancer antigen protein MAGE-A10.

TABLE 29 amino SEQ mass  mass Ex. acid ID spectrometry: spectrometry: No. sequence NO: LC-ESI/MS m/z Calculated 69 CQGLYDGMEHL 162 633.6 633.7 [M + 2H]²⁺ 70 CEGLYDGMEHL 163 634.3 634.2 [M + 2H]²⁺ 71 CGGLYDGMEHL 164 598.3 598.2 [M + 2H]²⁺ 72 CHGLYDGMEHL 165 638.3 638.2 [M + 2H]²⁺ 73 CIGLYDGMEHL 166 626.3 626.2 [M + 2H]²⁺ 74 CKGLYDGMEHL 167 633.9 633.7 [M + 2H]²⁺ 75 CFGLYDGMEHL 168 643.3 643.2 [M + 2H]²⁺ 76 CPGLYDGMEHL 169 618.3 618.2 [M + 2H]²⁺

TABLE 30  SEQ mass mass Ex. amino acid ID spectrometry: spectrometry: No. sequence No: LC-ESI/MS m/z Calculated 77 CTGLYDGMEHL 170 620.4 620.2 [M + 2H]²⁺ 78 CWGLYDGMEHL 171 662.8 662.7 [M + 2H]²⁺ 79 CYGLYDGMEHL 172 651.3 651.2 [M + 2H]²⁺ 80 CVGLYDGMEHL 173 619.3 619.2 [M + 2H]²⁺ 81 CRGLYDGMEHL 174 647.8 647.7 [M + 2H]²⁺ 82 CNGLYDGMEHL 175 626.8 626.7 [M + 2H]²⁺ 83 CDGLYDGMEHL 176 627.3 627.2 [M + 2H]²⁺ 84 CSGLYDGMEHL 177 613.3 613.2 [M + 2H]²⁺

Examples 85-103

By a method similar to that in Example 1, respective peptides consisting of the amino acid sequences of SEQ ID NOs: 178-196 were synthesized. Tables 31 and 32 show the result of mass spectrometry of each synthesized peptide.

All of the peptides in Tables 31 and 32 are the compounds of the present invention of the formula (1) wherein R¹ is a hydrogen atom, X^(a) is a divalent peptide group consisting of 1 amino acid residue, Y^(a) is a single bond, and cancer antigen peptide A is MAGE-A10₂₅₄₋₂₆₂ peptide (GLYDGMEHL) (SEQ ID NO: 19), which is a partial peptide of the cancer antigen protein MAGE-A10.

TABLE 31  SEQ mass mass Ex. amino acid  ID spectrometry: spectrometry: No. sequence No: LC-ESI/MS m/z Calculated 85 QCGLYDGMEHL 178 633.8 633.7 [M + 2H]²⁺ 86 PCGLYDGMEHL 179 918.3 618.2 [M + 2H]²⁺ 87 SCGLYDGMEHL 180 913.2 613.2 [M + 2H]²⁺ 88 TCGLYDGMEHL 181 620.3 620.2 [M + 2H]²⁺ 89 WCGLYDGMEHL 182 662.8 662.7 [M + 2H]²⁺ 90 YCGLYDGMEHL 183 651.4 651.2 [M + 2H]²⁺ 91 VCGLYDGMEHL 184 619.3 619.2 [M + 2H]²⁺ 92 ACGLYDGMEHL 185 605.3 605.2 [M + 2H]²⁺ 93 RCGLYDGMEHL 186 647.9 647.7 [M + 2H]²⁺ 94 NCGLYDGMEHL 187 626.8 626.7 [M + 2H]²⁺

TABLE 32  SEQ mass mass Ex. amino acid  ID spectrometry: spectrometry: No. sequence No: LC-ESI/MS m/z Calculated 95 DCGLYDGMEHL 188 627.2 627.2 [M + 2H]²⁺ 96 ECGLYDGMEHL 189 634.3 634.2 [M + 2H]²⁺ 97 GCGLYDGMEHL 190 598.1 598.2 [M + 2H]²⁺ 98 HCGLYDGMEHL 191 638.4 638.2 [M + 2H]²⁺ 99 ICGLYDGMEHL 192 626.3 626.2 [M + 2H]²⁺ 100 LCGLYDGMEHL 193 626.4 626.2 [M + 2H]²⁺ 101 KCGLYDGMEHL 194 633.9 633.7 [M + 2H]²⁺ 102 MCGLYDGMEHL 195 635.4 635.2 [M + 2H]²⁺ 103 FCGLYDGMEHL 196 643.4 643.2 [M + 2H]²⁺

Experimental Example 6 Test of Trimming of N-Terminal Amino Acid by ERAP1

The peptides synthesized in Examples 31-49 were evaluated for N-terminal amino acid trimming efficiency using ERAP1. 50 μl of ERAP1 solution (50 μg/ml) in pH 8.0, 20 mM Tris.HCl-100 mM NaCl buffer (Tris.HCl buffer) was added to 1.42 μl of Tris.HCl buffer. 10 mM peptide solution in DMSO (2.0 μl) and 6.0 μL of DMSO were added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at 30° C. 1.0 hr later, 50 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide [HER2/neu₃₆₉_3₇₇ peptide (KIFGSLAFL) (SEQ ID NO: 53)] obtained by trimming was determined based on the obtained AUC, and is shown in Table 33.

analysis conditions pump: UFLC manufactured by Shimadzu column: Shim-pack XR-ODS 3.0 mmi.d.×75 mm solution: 0.05% TFA H₂O(A)-0.05% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: Concentration of SOLUTION B was raised from 10% to 70% from 0.0 min to 5.0 min

TABLE 33  SEQ formation rate amino acid  ID of KIFGSLAFL Example sequence NO: (SEQ ID NO: 53)(%) 31 ACKIFGSLAFL 124 6.6 32 RCKIFGSLAFL 125 0.0 33 NCKIFGSLAFL 126 5.8 34 DCKIFGSLAFL 127 7.6 35 QCKIFGSLAFL 128 12.3 36 ECKIFGSLAFL 129 20.1 37 GCKIFGSLAFL 130 11.2 38 HCKIFGSLAFL 131 0.0 39 ICKIFGSLAFL 132 4.8 40 LCKIFGSLAFL 133 4.8 41 KCKIFGSLAFL 134 0.0 42 MCKIFGSLAFL 135 4.5 43 FCKIFGSLAFL 136 2.6 44 PCKIFGSLAFL 137 4.3 45 SCKIFGSLAFL 138 19.6 46 TCKIFGSLAFL 139 15.9 47 WCKIFGSLAFL 140 0.9 48 YCKIFGSLAFL 141 5.5 49 VCKIFGSLAFL 142 5.1

Experimental Example 7 Measurement of Solubility Step 1. Preparation of Isotonic Buffer

1. 75% aqueous solution of disodium hydrogen phosphate and 5.53% aqueous solution of citric acid were mixed to prepare buffers of pH 6.0 and 7.4.

Step 2. Preparation of Test Solution

To prepare a test solution, about 1 mg of a test product was measured and the isotonic buffer (0.5 mL) was added thereto. The prepared solution was shaken at room temperature for 90 min (shaking conditions: RECIPRO SHAKER SR-1N manufactured by TAITEC, Speed=8), centrifuged (15000 rpm, 5 min, room temperature), and the supernatant after centrifugation was used as a test solution.

Step 3. Preparation of Standard Solution

About 1 mg of the test product was accurately measured, dissolved in 0.1% TFA water/acetonitrile=1/1, made the total amount 10 mL, and this was used as a standard solution of the test product.

Step 4. Measurement of Concentration of Test Product

The standard solution of the test product and the test solution are analyzed by HPLC (under the analysis conditions described in Table 34), and the solubility of the test product is calculated from the ratio of peak area compared to the standard solution.

HPLC measurement conditions column: Chemcopack Quicksorb (4.6 mmφ×150 mm, 5 μm) manufactured by Chemco Scientific Co., Ltd. mobile phase: SOLUTION A; 0.1% TFA water, SOLUTION B; 0.1% TFA acetonitrile solution column temperature: room temperature flow rate: 1 mL/min detection wavelength: UV 254 nm, 230 nm (2 wavelength detection) sample injection volume: 10 μL

TABLE 34 gradient analysis conditions time (min) SOLUTION A (%) SOLUTION B (%) 0.00 80 20 10.00 0 100 15.00 0 100 15.01 80 20 25.00 80 20 25.01 STOP

The respective peptides consisting of the amino acid sequences of SEQ ID NOs: 19, 87 and 53 and the compound represented by the formula (4) (conjugate) synthesized in Example 29 were subjected to the above-mentioned solubility measurement. Each solubility is shown in Table 35.

SEQ ID NO: or Ex. amino acid sequence or formula pH 6.0 pH 7.4 No. structural formula No. (mg/mL) (mg/mL) — GLYDGMEHL SEQ ID NO: 19 >1.0 >1.0 — VYGFVRACL SEQ ID NO: 87 >1.0 >1.0 — KIFGSLAFL SEQ ID NO: 53 0.1 0.123 29

formula (4) 0.17 >1.0

Examples 104-105

By a method similar to that in Example 1, respective peptides consisting of the amino acid sequences of SEQ ID NOs: 197 and 198 were synthesized. Table 36 shows the result of mass spectrometry of each synthesized peptide.

All of the peptides in Table 36 are the compounds of the present invention of the formula (2) wherein X^(b) is a single bond, Y^(b) is a single bond, and cancer antigen peptide B is an HLA-DR-restricted universal cancer antigen peptide (SEQ ID NO: 101 or 102).

TABLE 36 SEQ mass mass Ex. amino acid  ID spectrometry: spectrometry: No. sequence No: LC-ESI/MS m/z Calculated 104 CAKFVAAWTLKAAA 197 726.5 726.4 [M + 2H]²⁺ 105 CaKFVAAWTLKAAa 198 726.4 726.4 [M + 2H]²⁺

Examples 106 and 107

By a method similar to that in Example 1, respective peptides consisting of the amino acid sequences of SEQ ID NOs: 199 and 200 were synthesized. Table 37 shows the result of mass spectrometry of each synthesized peptide.

All of the peptides in Table 37 are the compounds of the present invention of the formula (3) wherein X^(c) is a single bond, Y^(c) is a single bond, and cancer antigen peptide C is an HLA-DR-restricted universal cancer antigen peptide (SEQ ID NO: 101 or 102).

TABLE 37  SEQ mass mass Ex. amino acid  ID spectrometry: spectrometry: No. sequence No: LC-ESI/MS m/z Calculated 106 AKFVAAWTLKAAAC 199 726.5 726.4 [M + 2H]²⁺ 107 aKFVAAWTLKAAaC 200 726.5 726.4 [M + 2H]²⁺

Example 108 Synthesis of the Compound Represented by

the formula (14):

By using the synthesis method described in step 1 of Example 29, H-Cys (Pys)-Lys-Ile-Phe-Gly-Ser-Leu-Ala-Phe-Leu-OH(SEQ ID NO: 247), i.e., the compound represented by the formula (14) was synthesized.

mass spectrometry: LC-ESI/MS m/z=1208.1[M+H]⁺ (Calculated=1208.5)

Examples 109-113

By using the synthesis method described in step 2 of Example 29 and the synthesis method described in Example 108, the compound (conjugate) represented by any of the formulas (5), (11) and (15)-(17) was synthesized. The results of mass spectrometry are shown in Table 38, wherein the bond between C and C is a disulfide bond.

mass spec- for- trometry: mass spec- Ex. mula LC-ESI/ trometry: No. structural formula No. MS m/z Calculated 109

11 1115.9 [M + 2H]²⁺ 1115.8 110

 5 1127.2 [M + 2H]²⁺ 1127.0 111

15 1274.5 [M + 2H]²⁺ 1274.6 112

16 850.0 [M + 3H]³⁺  850.1 113

17 1274.3 [M + 2H]²⁺ 1274.6

Examples 114-143

By a method similar to that in Example 1, peptides consisting of the amino acid sequences of SEQ ID NOs: 201-230 were synthesized. Tables 39-41 show the result of mass spectrometry of each synthesized peptide.

All of the peptides in Tables 39-41 are the compounds of the present invention of the formula (1) wherein R¹ is a hydrogen atom, X^(a) is a single bond, Y is a single bond, and cancer antigen peptide A is an MHC class I-restricted cancer antigen peptide shown in Tables 1-9.

TABLE 39  SEQ mass mass Ex. amino acid ID spectrometry: spectrometry: No. sequence No: LC-ESI/MS m/z Calculated 114 CGYDQIMPKI 201 584.8 584.7 [M + 2H]²⁺ 115 CGYDQIMPKK 202 592.3 592.2 [M + 2H]²⁺ 116 CSLLMWITQCFL 203 729.8 729.9 [M + 2H]²⁺ 117 CEYLQLVFGI 204 593.3 593.2 [M + 2H]²⁺ 118 CLIYRRRLMK 205 677.1 676.8 [M + 2H]²⁺ 119 CAFLPWHRLF 206 645.8 645.9 [M + 2H]²⁺ 120 CYMDGTMSQV 207 1135.3 1134.6 [M + H]⁺ 121 CAAGIGILTV 208 918.1 917.7 [M + H]⁺ 122 CFLWGPRALV 209 581.7 581.6 [M + 2H]²⁺ 123 CAYACNTSTL 210 1047.2  1046.6 [M + H]⁺

TABLE 40  SEQ mass mass Ex. amino acid ID spectrometry: spectrometry: No. sequence No: LC-ESI/MS m/z Calculated 124 CKWFPSCQFLL 211 686.8 686.9 [M + 2H]²⁺ 125 CNYKHCFPEI 212 627.7 627.8 [M + 2H]²⁺ 126 CYLSGANLNL 213 534.6 534.6 [M + 2H]²⁺ 127 CAYIDFEMKI 214 617.2 617.1 [M + 2H]²⁺ 128 CQLSLLMWIT 215 604.8 604.9 [M + 2H]²⁺ 129 CAEEAAGIGIL 216 524.1 524.1 [M + 2H]²⁺ 130 CSNDGPTLI 217 920.0 919.5 [M + H]⁺ 131 CKCDICTDEY 218 597.2 597.2 [M + 2H]²⁺ 132 CHLFGYSWYK 219 652.7 652.8 [M + 2H]²⁺ 133 CWQYFFPVIF 220 675.8 675.8 [M + 2H]²⁺

TABLE 41  SEQ mass mass Ex. amino acid ID spectrometry: spectrometry: No. sequence No: LC-ESI/MS m/z Calculated 134 CKTWGQYWQV 221 350.2 650.3 [M + 2H]²⁺ 135 CSEIWRDIDF 222 642.7 642.6 [M + 2H]²⁺ 136 CVLRENTSPK 223 574.2 574.2 [M + 2H]²⁺ 137 CSTAPPAHGV 224 470.5 470.5 [M + 2H]²⁺ 138 CSTAPPVHNV 225 513.1 513.1 [M + 2H]²⁺ 139 CVYFFLPDHL 226 627.7 627.9 [M + 2H]²⁺ 140 CASGPGGGAPR 227 465.5 465.5 [M + 2H]²⁺ 141 CMEVDPIGHLY 228 639.2 639.4 [M + 2H]²⁺ 142 CTFPDLESEF 229 1188.3 1187.7 [M + H]⁺ 143 CEADPIGHLY 230 559.6 559.8 [M + 2H]²⁺

Experimental Example 8

The compounds represented by the formulas (5), (11) and (15)-(17) (conjugates) synthesized in Examples 109-113 were subjected to the solubility measurement shown in Experimental Example 7. Each solubility is shown in Table 42.

TABLE 42 SEQ ID NO: or pH 6.0 pH 7.4 Ex. amino acid sequence or formula (mg/ (mg/ No. structural formula No. mL) mL) 109

11 0.179 0.7 110

 5 0.511 >1.0 111

15 <0.001 <0.001 112

16 <0.001 0.002 113

17 <0.001 0.002

Experimental Example 9 Test of Trimming of N-Terminal Amino Acid by ERAP1

The peptides synthesized in Examples 69-84 were evaluated for N-terminal amino acid trimming efficiency using ERAP1. 50 μl of ERAP1 solution (10 μg/ml) in pH 8.0, 20 mM Tris.HCl-1.00 mM NaCl buffer (Tris.HCl buffer) was added to 142 μl of Tris.HCl buffer. 10 mM peptide solution in DMSO (2.0 μl) and 6.0 μL of DMSO were added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at 30° C. 1.0 hr later, 50 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide (MAGE-A10₂₅₄₋₂₆₂ peptide (GLYDGMEHL) (SEQ ID NO: 19)) obtained by trimming was determined based on the obtained AUC, and is shown in Tables 43 and 44.

analysis conditions pump: UFLC manufactured by Shimadzu column: Kinetex 2.6 u C18 100A 3.0 mmi.d.×75 mm solution: 0.1% TFA H₂O(A)-0.1% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: concentration of SOLUTION B was raised from 10% to 50% from 0.0 min to 8.5 min

TABLE 43  formation rate Ex. SEQ ID of GLYDGMEHL No. amino acid sequence NO: (SEQ ID NO: 19)(%) 69 CQGLYDGMEHL 162 56.9  70 CEGLYDGMEHL 163 6.2 71 CGGLYDGMEHL 164 0.0 72 CHGLYDGMEHL 165 0.0 73 CIGLYDGMEHL 166 0.4 74 CKGLYDGMEHL 167 0.0 75 CFGLYDGMEHL 168 0.0 76 CPGLYDGMEHL 169 0.0

TABLE 44  formation rate Ex. SEQ ID of GLYDGMEHL No. amino acid sequence NO: (SEQ ID NO: 19)(%) 77 CTGLYDGMEHL 170 89.4 78 CWGLYDGMEHL 171 0.0 79 CYGLYDGMEHL 172 0.0 80 CVGLYDGMEHL 173 0.0 81 CRGLYDGMEHL 174 0.0 82 CNGLYDGMEHL 175 82.2 83 CDGLYDGMEHL 176 25.0 84 CSGLYDGMEHL 177 1.1

Experimental Example 10 Test of Trimming of N-Terminal Amino Acid by ERAP1

The peptides synthesized in Examples 85-103 were evaluated for N-terminal amino acid trimming efficiency using ERAP1. 50 μl of ERAP1 solution (10 μg/ml) in pH 8.0, 20 mM Tris.HC-1.00 mM NaCl buffer (Tris.HCl buffer) was added to 142 μl of Tris.HCl buffer. 1.0 mM peptide solution in DMSO (2.0 μl) and 6.0 μL of DMSO were added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at 30° C. 1.0 hr later, 50 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide [MAGE-A10₂₅₄₋₂₆₂ peptide (GLYDGMEHL) (SEQ ID NO: 19)] obtained by trimming was determined based on the obtained AUC, and is shown in Tables 45 and 46.

analysis conditions pump: UFLC manufactured by Shimadzu column: Kinetex 2.6 u C18 100A 3.0 mmi.d.×75 mm solution: 0.1% TFA H₂O(A)-0.1% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: concentration of SOLUTION B was raised from 10% to 50% from 0.0 min to 8.5 min

TABLE 45  SEQ formation rate Ex. ID of GLYDGMEHL No. amino acid sequence NO: (SEQ ID NO: 19)(%) 85 QCGLYDGMEHL 178 3.6 86 PCGLYDGMEHL 179 19.2 87 SCGLYDGMEHL 180 22.2 88 TCGLYDGMEHL 181 7.3 89 WCGLYDGMEHL 182 0.0 90 YCGLYDGMEHL 183 5.7 91 VCGLYDGMEHL 184 2.4 92 ACGLYDGMEHL 185 5.2 93 RCGLYDGMEHL 186 0.0

TABLE 46  SEQ formation rate Ex. ID of GLYDGMEHL No. amino acid sequence NO: (SEQ ID NO: 19)(%) 94 NCGLYDGMEHL 187 18.2 95 DCGLYDGMEHL 188 3.2 96 ECGLYDGMEHL 189 2.9 97 GCGLYDGMEHL 190 10.4 98 HCGLYDGMEHL 191 0.0 99 ICGLYDGMEHL 192 0.0 100 LCGLYDGMEHL 193 0.0 101 KCGLYDGMEHL 194 0.0 102 MCGLYDGMEHL 195 5.8 103 FCGLYDGMEHL 196 17.6

Experimental Example 11 Test of Trimming of N-Terminal Amino Acid by ERAP1

The peptides synthesized in Examples 50, 56, 64 and 67 were evaluated for N-terminal amino acid trimming efficiency using ERAP1. 50 μl of ERAP1 solution (10 μg/ml) in pH 8.0, 20 mM Tris.HCl-100 mM NaCl buffer (Tris.HCl buffer) was added to 142 μl of Tris.HCl buffer. 10 mM peptide solution in DMSO (2.0 μl) and 6.0 μL of DMSO were added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at 30° C. 1.0 hr later, 50 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide (Proteinase-3₁₆₉₋₁₇₇ peptide (VLQELNVTV) (SEQ ID NO: 43) obtained by trimming was determined based on the obtained AUC, and is shown in Table 47.

analysis conditions pump: UFLC manufactured by Shimadzu column: Kinetex 2.6 u C18 100A 3.0 mmi.d.×75 mm solution: 0.1% TFA H₂O(A)-0.1% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: concentration of SOLUTION B was raised from 10% to 50% from 0.0 min to 8.5 min

TABLE 47  SEQ formation rate Ex. ID of VLQELNVTV No. amino acid sequence NO: (SEQ ID NO: 43)(%) 50 ACVLQELNVTV 143 1.8 56 GCVLQELNVTV 149 1.1 64 SCVLQELNVTV 157 1.3 67 YCVLQELNVTV 160 0.7

Experimental Example 12 Test of Trimming of N-Terminal Amino Acid by ERAP1

The peptides synthesized in Examples 114, 11.5, 118-122, 126, 129, 132, 137, 139 and 141-143 were evaluated for N-terminal amino acid trimming efficiency using ERAP1. 50 μl of ERAP1 solution (10 μg/ml) in pH 8.0, 20 mM Tris.HCl-100 mM NaCl buffer (Tris.HCl buffer) was added to 142 μl of Tris.HCl buffer. 10 mM peptide solution in DMSO (2.0 μl) and 6.0 μL of DMSO were added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at 30° C. 1.0 hr later, 50 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide obtained by trimming was determined based on the obtained AUC, and is shown in Tables 48 and 49.

analysis conditions pump: UFLC manufactured by Shimadzu column: Kinetex 2.6 u C18 100A 3.0 mmi.d.×75 mm solution: 0.1% TFA H₂O (A)-0.1% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: concentration of SOLUTION B was raised from 10% to 50% from 0.0 min to 8.5 min

TABLE 48  Ex. amino acid SEQ ID sequence formation No. sequence NO: to be formed rate (%) 114 CGYDQIMPKI 201 GYDQIMPKI 6.4 115 CGYDQIMPKK 202 GYDQIMPKK 1.1 118 CLIYRRRLMK 205 LIYRRRLMK 3.0 119 CAFLPWHRLF 206 AFLPWHRLF 7.8 120 CYMDGTMSQV 207 YMDGTMSQV 21.5 121 CAAGIGILTV 208 AAGIGILTV 7.2 122 CFLWGPRALV 209 FLWGPRALV 2.8

TABLE 49 Ex. amino acid SEQ ID sequence formation No. sequence NO: to be formed rate (%) 126 CYLSGANLNL 213 YLSGANLNL 15.2 129 CAEEAAGIGIL 216 AEEAAGIGIL  5.2 132 CHLFGYSWYK 219 HLFGYSWYK  1.4 137 CSTAPPAHGV 224 STAPPAHGV  6.9 139 CVYFFLPDHL 226 VYFFLPDHL  5.6 141 CMEVDPIGHLY 228 MEVDPIGHLY 20.6 142 CTFPDLESEF 229 TFPDLESEF 16.8 143 CEADPIGHLY 230 EADPIGHLY  1.7

Examples 144-146

By a method similar to that in Example 29, the compound (conjugate) represented by any of the formulas (7)-(9) was synthesized. The results of mass spectrometry are shown in Table 50, wherein the bond between C and C is a disulfide bond.

TABLE 50 mass mass spec- spectro- for- trometry: metry: Ex. mula LC-ESI/ Calc- No. structural formula No. MS m/z ulated 144

9 1293.9 [M + 2H]²⁺ 1294.0 145

8 1293.7 [M + 2H]²⁺ 1294.0 146

7 1293.6 [M + 2H]²⁺ 1294.0

Experimental Example 13

Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The compound represented by the formula (11) synthesized in Example 109 was evaluated for the CTL induction ability by an in vivo CTL induction test using an HLA-A0201 transgenic mouse. The compound represented by the formula (11):

wherein the bond between C and C is a disulfide bond, is, in particular, a compound of the aforementioned formula (1) wherein cancer antigen peptide A is GLYDGMEHL (SEQ ID NO: 19) and cancer antigen peptide D is SLLMWITQC (SEQ ID NO: 88). GLYDGMEHL (SEQ ID NO: 19) and SLLMWITQC (SEQ ID NO: 88) are HLA-A0201-restricted cancer antigen peptides.

The HLA-A0201 transgenic mouse is as described in Experimental Example 4.

To evaluate whether CTLs to each of the peptides (SEQ ID NOs: 19 and 88) endogenously presented by cancer cells was induced, the compound represented by the formula (11) was administered to the HLA-A0201 transgenic mouse. That is, it was determined whether IFNγ production was observed by re-stimulation, with the peptide (SEQ ID NO: 19 or 88), of the splenocyte derived from the above-mentioned mouse administered with the compound represented by the formula (11).

Specifically, the compound represented by the formula (11) was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 10 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 250 μg/site. One week later, the mouse was euthanized with CO₂ gas, the spleen was isolated, and splenocytes were prepared. IFNγ ELISPOT assay kit was used for the measurement of IFNγ production. On the previous day of splenocyte preparation, an ELISPOT plate was treated with an anti-mouse IFNγ antibody, and blocked with RPMI1640 medium containing 10% FBS the next day. The prepared HLA-A0201 transgenic mouse-derived splenocytes were plated at 0.25×10⁶ cells/well on the blocked ELISPOT plate. Each of the peptide (SEQ ID NO: 19 and 88) was dissolved in DMSO at 40 mg/mL, and further diluted with RPMI1640 medium containing 10% FBS to 40 μg/mL. The HLA-A0201 transgenic mouse-derived splenocytes were pulsed with the diluted peptide represented by SEQ ID NO: 19 or SEQ ID NO: 88 (final concentration: 10 μg/mL), and cultivated for 17 hr at 37° C., 5% CO₂, whereby peptide re-stimulation in vitro was performed. After the culture, the supernatant was removed, and the ELISPOT plate was allowed to develop color according to the attached protocol. The number of spots that developed color was measured by ImmunoSpot Analyzer (manufactured by C.T.L.).

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIG. 11.

In FIG. 11, the vertical axis shows the number of cells that responded among the plated cells. In FIG. 11, the black bar and the shaded bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes while being pulsed with the peptides shown by SEQ ID NOs: 19 and 88, respectively, and the white bar show the result of culture without pulsing. That is, the difference in the values of the black or shaded bar and the white bar shows the number of peptide-specific CTLs, and that the administration of the compound represented by the formula (11) resulted in the induction of CTLs specific to each of the peptides shown by SEQ ID NOs: 19 and 88 in vivo in the mouse.

In FIG. 11, the value of the white bar is not detected. This means that the splenocytes of the HLA-A0201 transgenic mouse did not react at all in the absence of pulsing with the peptide of interest. As a result of this test, IFNγ production specific to each of the peptides shown by SEQ ID NOs: 19 and 88 was detected in the HLA-A0201 transgenic mouse-derived splenocytes.

From the above, it was demonstrated that the compound represented by the formula (11) can induce CTLs specific to each of the peptides shown by SEQ ID NOs: 19 and 88. It was strongly suggested that the compound represented by the formula (11) undergoes cleavage of disulfide bond and appropriate trimming by ERAP-1 in mice in vivo and is indeed processed into the peptides shown by SEQ ID NOs: 19 and 88.

That is, it was demonstrated that the compound represented by the formula (11), which is one embodiment of the compound of the present invention, is a conjugate wherein two different peptides form a composite via the disulfide bond shown in the formula (1), and is a cancer antigen peptide conjugate vaccine that indeed can induce different two types of CTLs in vivo.

Experimental Example 14

Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The compound represented by the formula (5) synthesized in Example 110 was evaluated for the CTL induction ability by an in vivo CTL induction test using HLA-A0201 transgenic mouse. The compound represented by the formula (5):

wherein the bond between C and C is a disulfide bond, is, in particular, a compound of the aforementioned formula (1) wherein cancer antigen peptide A is GLYDGMEHL (SEQ ID NO: 19) and cancer antigen peptide A is VLQELNVTV (SEQ ID NO: 43). GLYDGMEHL (SEQ ID NO: 19) and VLQELNVTV (SEQ ID NO: 43) are HLA-A0201-restricted cancer antigen peptides.

The HLA-A0201 transgenic mouse is as described in Experimental Example 4.

To evaluate whether CTLs to each of the peptides (SEQ ID NOs: 19 and 43) endogenously presented by cancer cells was induced, the compound represented by the formula (5) was administered to the HLA-A0201 transgenic mouse. That is, it was determined whether IFNγ production was observed by re-stimulation, with the peptide (SEQ ID NO: 19 or 43), of the splenocyte derived from the above-mentioned mouse administered with the compound represented by the formula (5).

Specifically, the compound represented by the formula (5) was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 10 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 250 μg/site. One week later, the mouse was euthanized with CO₂ gas, the spleen was isolated, and splenocytes were prepared. IFNγ ELISPOT assay kit was used for the measurement of IFNγ production. On the previous day of splenocyte preparation, an ELISPOT plate was treated with an anti-mouse IFNγ antibody, and blocked with RPMI1640 medium containing 10% FBS the next day. The prepared HLA-A0201 transgenic mouse-derived splenocytes were plated at 0.25×10⁶ cells/well on the blocked ELISPOT plate. Each of the peptide (SEQ ID NO: 19 or 43) was dissolved in DMSO at 40 mg/mL, and further diluted with RPMI1640 medium containing 10% FBS to 40 μg/mL. The HLA-A0201 transgenic mouse-derived splenocytes were pulsed with the diluted peptide represented by SEQ ID NO: 19 or SEQ ID NO: 43 (final concentration: 10 μg/mL), and cultivated for 17 hr at 37° C., 5% CO₂, whereby peptide re-stimulation in vitro was performed. After the culture, the supernatant was removed, and the ELISPOT plate was allowed to develop color according to the attached protocol. The number of spots that developed color was measured by ImmunoSpot Analyzer (manufactured by C.T.L.).

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIG. 12.

In FIG. 12, the vertical axis shows the number of cells that responded among the plated cells. In FIG. 12, the black bar and the shaded bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes while being pulsed with the peptides shown by SEQ ID NOs: 19 and 43, respectively, and the white bar show the result of culture without pulsing. That is, the difference in the values of the black or shaded bar and the white bar shows the number of peptide-specific CTLs, and that the administration of the compound represented by the formula (5) resulted in the induction of CTLs specific to each of the peptides shown by SEQ ID NO: 19 and 43 in vivo in the mouse.

In FIG. 12, the value of the white bar is not detected. This means that the splenocytes of the HLA-A0201 transgenic mouse did not react in the absence of pulsing with the peptide of interest. As a result of this test, IFNγ production specific to each of the peptides shown by SEQ ID NOs: 19 and 43 was detected in the HLA-A0201 transgenic mouse-derived splenocytes.

From the above, it was demonstrated that the compound represented by the formula (5) can induce CTLs specific to each of the peptides shown by SEQ ID NOs: 19 and 43. It was strongly suggested that the compound represented by the formula (5) undergoes cleavage of disulfide bond and appropriate trimming by ERAP-1 in mice in vivo and is indeed processed into the peptides shown by SEQ ID NOs: 19 and 43.

That is, it was demonstrated that the compound represented by the formula (5), which is one embodiment of the compound of the present invention, is a conjugate wherein two different peptides form a composite via the disulfide bond shown in the formula (1), and is a cancer antigen peptide conjugate vaccine that indeed can induce different two types of CTLs in vivo.

Experimental Example 15 Test of Trimming of N-Terminal Amino Acid by ERAP1

The peptides synthesized in Examples 123-125, 130, 134, 135 and 138 were evaluated for N-terminal amino acid trimming efficiency using ERAP1. 50 μl of ERAP1 solution (50 μg/ml) in pH 8.0, 20 mM Tris.HCl-100 mM NaCl buffer (Tris.HCl buffer) was added to 142 μl of Tris.HCl buffer. 10 mM peptide solution in DMSO (2.0 μl) and 6.0 μL of DMSO were added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at 30° C. 1.0 hr later, 50 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide obtained by trimming was determined based on the obtained AUC, and is shown in Table 51.

analysis conditions pump: UFLC manufactured by Shimadzu column: Kinetex 2.6 u C18 100A 3.0 mmi.d.×75 mm solution: 0.1% TFA H₂O (A)-0.1% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: concentration of SOLUTION B was raised from 10% to 50% from 0.0 min to 8.5 min

TABLE 51 Ex. amino acid SEQ ID sequence formation No. sequence NO: to be formed rate (%) 123 CAYACNTSTL 210 AYACNTSTL 21.8 124 CKWFPSCQFLL 211 KWFPSCQFLL  4.0 125 CNYKHCFPEI 212 NYKHCFPEI 13.9 130 CSNDGPTLI 217 SNDGPTLI 26.0 134 CKTWGQYWQV 221 KTWGQYWQV  5.8 135 CSEIWRDIDF 222 SEIWRDIDF  3.6 138 CSTAPPVHNV 225 STAPPVHNV 71.2

Experimental Example 16 Test of Trimming of N-Terminal Amino Acid by ERAP1

The peptides synthesized in Example 140 were evaluated for N-terminal amino acid trimming efficiency using ERAP1. 50 μl of ERAP1 solution (50 μg/ml) in pH 8.0, 20 mM Tris.HCl-100 mM NaCl buffer (Tris.HCl buffer) was added to 1.42 μl of Tris-HCl buffer. 10 mM peptide solution in DMSO (2.0 μl) and 6.0 μL of DMSO were added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at 30° C. 1.0 hr later, 50 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide obtained by trimming was determined based on the obtained AUC, and is shown in Table 52.

analysis conditions pump: UFLC manufactured by Shimadzu column: Kinetex 2.6 u C18 100A 3.0 mmi.d.×75 mm solution: 0.1% TFA H₂O(A)-0.1% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: concentration of SOLUTION B was raised from 1% to 30% from 0.0 min to 8.5 min

TABLE 52 Ex. amino acid SEQ ID sequence formation No. sequence NO: to be formed rate (%) 140 CASGPGGGAPR 227 ASGPGGGAPR 11.0

Experimental Example 17 Test of Trimming of N-Terminal Amino Acid by ERAP1

The peptides synthesized in Example 131 were evaluated for N-terminal amino acid trimming efficiency using ERAP1. 50 μl of ERAP1 solution (100 μg/ml) in pH 8.0, 20 mM Tris.HCl-100 mM NaCl buffer (Tris.HCl buffer) was added to 142 μl of Tris.HCl buffer. 10 mM peptide solution in DMSO (8.0 μl) was added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at 30° C. 1.0 hr later, 10 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide obtained by trimming was determined based on the obtained AUC, and is shown in Table 53.

analysis conditions pump: UFLC manufactured by Shimadzu column: Kinetex 2.6 u C18 100A 3.0 mmi.d.×75 mm solution: 0.1% TFA H₂O(A)-0.1% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: concentration of SOLUTION B was raised from 10% to 50% from 0.0 min to 8.5 min

TABLE 53 Ex. amino acid SEQ ID sequence formation No. sequence NO: to be formed rate (%) 131 CKCDICTDEY 218 KCDICTDEY 13.2

Experimental Example 18 Test of Trimming of N-Terminal Amino Acid by ERAP1

The peptides synthesized in Example 136 were evaluated for N-terminal amino acid trimming efficiency using ERAP. 50 μl of ERAP1 solution (100 μg/ml) in pH 8.0, 20 mM Tris.HCl-100 mM NaCl buffer (Tris.HCl buffer) was added to 142 μl of Tris.HCl buffer. 10 mM peptide solution in DMSO (8.0 μl) was added to the aforementioned ERAP1 solution, and the mixture was blended well and stood at 30° C. 1.0 hr later, 10 μl of the mixture was injected into UFLC (under the analysis conditions shown below), and AUC of the peptide of interest was determined. The peptide to be obtained by trimming was chemically synthesized separately, and analyzed under similar conditions in the absence of the enzyme. The formation ratio of the peptide obtained by trimming was determined based on the obtained AUC, and is shown in Table 54.

analysis conditions pump: UFLC manufactured by Shimadzu column: Kinetex 2.6 u C18 100A 3.0 mmi.d.×75 mm solution: 0.1% TFA H₂O(A)-0.1% TFA CH₃CN(B) oven temperature: 40° C. flow rate: 1.0 ml/min detection wavelength: λ=220 nm gradient: concentration of SOLUTION B was raised from 1% to 30% from 0.0 min to 8.5 min

TABLE 54 Ex. amino acid SEQ ID sequence formation No. sequence NO: to be formed rate (%) 136 CVLRENTSPK 223 VLRENTSPK 20.8

Examples 147-148

By a method similar to that in Example 29, the compound (conjugate) represented by any of the formulas (12) and (18) was synthesized. The results of mass spectrometry are shown in Table 55, wherein the bond between C and C is a disulfide bond.

TABLE 55 mass mass spec- spectro- trometry: metry: Ex. formula LC-ESI/ Calc- No. structural formula No. MS m/z ulated 147

18 637.5 [M + 3H]³⁺ 637.8 148

12 677.0 [M + 3H]³⁺ 677.3

Reference Examples 2-9

By a method similar to that in Example 1, peptides consisting of the amino acid sequences of SEQ ID NOs: 231-238 were synthesized. Table 56 shows the result of mass spectrometry of each synthesized peptide.

The compounds of SEQ ID NOs: 231-238 were not the compounds of the present invention and were therefore described as Reference Example.

TABLE 56 mass mass Ref. SEQ spectrometry: spec- Ex. amino acid ID LC-ESI/ trometry: No. sequence NO: MS m/z Calculated 2 GLYDGMEHLKIFG 231 1006.4 1007.2 SLAFL [M + 2H]²⁺ 3 KIFGSLAFLGLYD 232  671.3  671.5 GMEHL [M + 3H]³⁺ 4 GLYDGMEHLGGGG 233  785.3  785.6 GGKIFGSLAFL [M + 3H]³⁺ 5 KIFGSLAFLGGGG 234  785.3  785.6 GGGLYDGMEHL [M + 3H]³⁺ 6 VYGFVRACLGLYD 235  681.9  682.1 GMEHL [M + 3H]³⁺ 7 GLYDGMEHLVYGF 236  681.9  682.1 VRACLACL [M + 3H]³⁺ 8 VYGFVRACLGGGG 237  796.0  796.2 GGGLYDGMEHL [M + 3H]³⁺ 9 GLYDGMEHLGGGG 238  796.0   796.2 GGVYGFVRACL [M + 3H]³⁺

The peptides represented by SEQ ID NOs: 233, 234, 237 and 238 shown in Table 56 were synthesized by referring to the non-patent document, Cancer Science January 2012, Vol. 103, no. 1, 150-153.

Example 149

Synthesis of the Compound Represented by the Formula (19):

wherein the bond between C and C is a disulfide bond

Step 1. Synthesis of Fmoc-Cys (Mmt)-Ala-SBn (Mmt is 4-Methoxytrityl) (Synthesis of Fmoc-C(Mmt)A-SBn)

A solution of Fmoc-Cys (Mmt)-OH (4.80 g), N,N-diisopropylethylamine (2.56 mL), hexafluorophosphoric acid (benzotriazol-1-yloxy)tripyrrolidinophosphonium (4.50 g) and H-Ala-SBn synthesized by a known method (for example, Journal of Organic Chemistry, Vol. 64, No. 24 8761-8769) in chloroform (20 ml) was stirred at room temperature for 1 hr. The reaction mixture was purified by column chromatography (elution solvent, hexane/ethyl acetate) to give the desired compound, Fmoc-C(Mmt)A-SBn (2.80 g).

NMR: ¹H NMR (CDCl₃)δ 7.72 (t, J=7.6 Hz, 2H), 7.54 (d, J=7.2 Hz, 1H), 7.38-7.34 (m, 7H), 7.29-7.25 (m, 6H), 7.23-7.15 (m, 7H), 6.76 (d, J=8.8 Hz, 2H), 6.15 (d, J=8.0 Hz, 1H), 4.95 (d, J=7.2 Hz, 1H), 4.57 (quin, J=7.6 Hz, 1H), 4.35 (d, J=6.8 Hz, 2H) 4.19-4.17 (m, 1H), 4.04 (s, 2H), 3.73 (s, 3H), 2.72 (dd, J=13.2, 8.4 Hz, 1H), 2.61 (d, J=9.6 Hz, 1H), 1.31 (d, J=7.2 Hz, 3H).

(SEQ ID NO: 248) step 2. Synthesis of H-Cys(Mmt)-Ala-Cys-Gly-Leu- Tyr-Asp-Gly-Met-Glu-His-Leu-OH (Synthesis of C(Mmt)ACGLYDGMEHL)

A solution of Fmoc-Cys(Mmt)-Ala-SBn (11 mg) obtained in step 1, H-Cys-Gly-Leu-Tyr-Asp-Gly-Met-Glu-His-Leu-OH(SEQ ID NO: 98) (16 mg) synthesized in Example 25, N,N-diisopropylethylamine (200 μL), 3,3′,3″-Phosphanetriyl tripropanoic acid hydrochloride (1 mg), 4-mercaptophenylacetic acid (1 mg) and 0.1M sodium phosphate buffer (pH 7.5, 200 μL) in DMF (400 μL) was stirred at room temperature for 4 hr. To the reaction mixture was added diethylamine (200 μL) and the mixture was further stirred for 15 min. The reaction mixture was purified by reversed-phase HPLC to give the desired compound, C(Mmt)ACGLYDGMEHL(SEQ ID NO: 248)(6 mg).

mass spectrometry: LC-ESI/MS m/z=792.7 [M+2H]²⁺ (Calculated=792.9)

Step 3. Synthesis of (H-Cys(Mmt)-Ala-Cys-Gly-Leu-Tyr-Asp-Gly-Met-Glu-His-Leu-OH) (H-Cys-Lys-Ile-Phe-Gly-Ser-Leu-Ala-Phe-Leu-OH) Disulfide Bond [i.e., Synthesis of the Compound Represented by the Formula (20):

wherein the bond between C and C is a disulfide bond.

A solution of H-Cys(Mmt)-Ala-Cys-Gly-Leu-Tyr-Asp-Gly-Met-Glu-His-Leu-OH(SEQ ID NO: 248)(19 mg) obtained in step 2 and (H-Cys(Pys)-Lys-Ile-Phe-Gly-Ser-Leu-Ala-Phe-Leu-OH(SEQ ID NO: 247) (15 mg) obtained in Example 108 in DMF (1 mL) was stirred at room temperature for 2 hr. The reaction mixture was purified by reversed-phase HPLC to give 19 mg of the desired compound, (H-Cys(Mmt)-Ala-Cys-Gly-Leu-Tyr-Asp-Gly-Met-Glu-His-Leu-OH) (H-Cys-Lys-Ile-Phe-Gly-Ser-Leu-Ala-Phe-Leu-OH) disulfide bond [i.e., a compound represented by the formula (20)].

mass spectrometry: LC-ESI/MS m/z=803.3 [M−Mmt+3]²⁺ (Calculated=803.3)

step 4. Synthesis of aKFVAAWTLKAAaC(Pys) (SEQ ID NO: 249)

aKFVAAWTLKAAaC(SEQ ID NO: 200) (138 mg) obtained in Example 107 and 2,2′-dipyridyl bisulfide (0.2 M isopropanol solution, 718 μL) in (20% (w/w) aqueous acetic acid solution)/(acetonitrile)=l/l (5 mL) solution were stirred at room temperature for 2 hr. 2,2′-Dipyridyl bisulfide (0.2 M isopropanol solution, 350 μL) was further added, and the mixture was stirred for 2 hr. The reaction mixture was purified by reversed-phase HPLC to give 34 mg of the desired compound, aKFVAAWTLKAAaC(Pys) (SEQ ID NO: 249).

mass spectrometry: LC-ESI/MS m/z=520.5 [M+3H]³⁺ (Calculated=521.0)

Step 5. Synthesis of a Compound Represented by the Formula (19):

wherein the bond between C and C is a disulfide bond

A solution of (H-Cys(Mmt)-Ala-Cys-Gly-Leu-Tyr-Asp-Gly-Met-Glu-His-Leu-OH) (H-Cys-Lys-Ile-Phe-Gly-Ser-Leu-Ala-Phe-Leu-OH) disulfide bond obtained in step 3 [i.e., a compound represented by the formula (20)] (40 mg), aKFVAAWTLKAAaC (Pys) (35 mg) obtained in step 4 and triisopropylsilane (30 μL) in trifluoroacetic acid (570 μL) was stirred at room temperature for 30 min. The reaction mixture was purified by reversed-phase HPLC to give the desired compound, a compound represented by the formula (19) (5 mg).

mass spectrometry: LC-ESI/MS m/z=1285.8 [M+3H]³⁺ (Calculated=1286.5)

Experimental Example 19

Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The compound represented by the formula (16) synthesized in Example 112 was evaluated for the CTL induction ability by an in vivo CTL induction test using an HLA-A0201 transgenic mouse. The compound represented by the formula (16):

wherein the bond between C and C is a disulfide bond, is, in particular, a compound of the aforementioned formula (1) wherein cancer antigen peptide A is KIFGSLAFL (SEQ ID NO: 53) and cancer antigen peptide B is aKFVAAWTLKAAa (SEQ ID NO: 102). KIFGSLAFL (SEQ ID NO: 53) is an HLA-A0201-restricted cancer antigen peptide, and aKFVAAWTLKAAa (SEQ ID NO: 102) is an HLA-DR-restricted universal cancer antigen peptide (i.e., helper peptide).

The HLA-A0201 transgenic mouse is as described in Experimental Example 4. Using this mouse, peptides capable of inducing CTLs in HLA-A02 positive humans can be selected, and also the activity of helper peptides capable of inducing helper T cells by binding to human HLA-DRB1*0101 to enhance CTL induction can be evaluated.

Whether the administration of the compound represented by the formula (16) results in the induction of CTLs specific to the peptide of interest (SEQ ID NO: 53) was determined based on the measurement of IFNγ production by re-stimulation, with the peptide (SEQ ID NO: 53), of the splenocytes derived from the above-mentioned mouse administered with the compound represented by the formula (16). Whether the helper peptide (SEQ ID NO: 102) works in the living body was determined by comparison of the numbers of IFNγ-producing cells obtained by re-stimulating the splenocytes derived from the mouse administered with the compound represented by the formula (16) and those derived from the mouse administered with the compound represented by SEQ ID NO: 53 with the peptide (SEQ ID NO: 53).

Specifically, the compound represented by the formula (16) was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 5.1 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 130 μg/site. One week later, the mouse was euthanized with CO₂ gas, the spleen was isolated, and splenocytes were prepared. IFNγ ELISPOT assay kit was used for the measurement of IFNγ production. On the previous day of splenocyte preparation, an ELISPOT plate was treated with an anti-mouse IFNγ antibody, and blocked with RPMI1640 medium containing 10% FBS the next day. The prepared HLA-A0201 transgenic mouse-derived splenocytes were plated at 0.125×10⁶ cells/well on the blocked ELISPOT plate. The peptide (SEQ ID NO: 53) was dissolved in DMSO at 40 mg/mL, and further diluted with RPMI1640 medium containing 10% FBS to 40 μg/mL. The HLA-A0201 transgenic mouse-derived splenocytes were pulsed with the diluted peptide represented by SEQ ID NO: 53 (final concentration: 10 μg/mL), and cultivated for 19 hr at 37° C., 5% CO₂, whereby peptide re-stimulation in vitro was performed. After the culture, the supernatant was removed, and the ELISPOT plate was allowed to develop color according to the attached protocol. The number of spots that developed color was measured by ImmunoSpot Analyzer (manufactured by C.T.L.).

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIG. 13. In FIG. 13, the vertical axis shows the number of cells that responded among the plated cells, and the horizontal axis shows the compound or peptide administered to the mouse. In FIG. 13, the black bar shows the result of culture of HLA-A0201 transgenic mouse-derived splenocytes while being pulsed with the peptide shown by SEQ ID NO: 53, and the white bar shows the results of culture without pulsing. That is, the difference in the values of the black bar and the white bar shows the number of peptide-specific CTLs, and that the administration of the peptide shown by SEQ ID NO: 53 or the compound represented by the formula (16) resulted in the induction of CTLs specific to the peptide shown by SEQ ID NO: 53 in vivo in the mouse. In FIG. 13, the value of the white bar is not detected. This means that the splenocytes of the HLA-A0201 transgenic mouse did not react at all in the absence of pulsing with the peptide of interest. As a result of this test, IFNγ production specific to the peptide shown by SEQ ID NO: 53 was detected in the HLA-A0201 transgenic mouse-derived splenocytes. Moreover, in FIG. 13, the number of IFNγ-producing cells specific to the peptide shown by SEQ ID NO: 53 induced by the administration of the compound represented by the formula (16) was higher than that induced by the administration of the peptide shown by SEQ ID NO: 53.

From the above, it was demonstrated that the compound represented by the formula (16) can induce CTLs specific to the peptide shown by SEQ ID NO: 53. Administration of the compound represented by the formula (16) induced more IFNγ producing cells specific to the peptide shown by SEQ ID NO: 53 than the administration of the peptide shown by SEQ ID NO: 53. It was assumed that induction of cells reactive with the helper peptide shown by SEQ ID NO: 102 produced from the compound represented by the formula (16) enhanced induction of CTLs specific to the peptide shown by SEQ ID NO: 53. Therefore, it was strongly suggested that the compound represented by the formula (16) undergoes cleavage of disulfide bond and appropriate trimming by ERAP-1 in mice in vivo and is indeed processed into the peptides shown by SEQ ID NOs: 53 and 102.

That is, it was demonstrated that the compound represented by the formula (16), which is one embodiment of the compound of the present invention, is a conjugate wherein two different peptides form a composite via the disulfide bond shown in the formula (1), and is a cancer antigen peptide conjugate vaccine that indeed can induce CTLs and helper peptide reactive cells in vivo.

Experimental Example 20 Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The compound represented by the formula (17) synthesized in Example 113 was evaluated for the CTL induction ability by an in vivo CTL induction test using HLA-A0201 transgenic mouse. The compound represented by the formula (17):

wherein the bond between C and C is a disulfide bond, is, in particular, a compound of the aforementioned formula (1) wherein cancer antigen peptide A is KIFGSLAFL (SEQ ID NO: 53) and cancer antigen peptide C is aKFVAAWTLKAAa (SEQ ID NO: 102). KIFGSLAFL (SEQ ID NO: 53) is an HLA-A0201-restricted cancer antigen peptide, and aKFVAAWTLKAAa (SEQ ID NO: 102) is an HLA-DR-restricted universal cancer antigen peptide (i.e., helper peptide).

The HLA-A0201 transgenic mouse is as described in Experimental Examples 4 and 19.

Whether the administration of the compound represented by the formula (17) results in the induction of CTLs specific to the peptide of interest (SEQ ID NO: 53) was determined based on the measurement of IFNγ production by re-stimulation, with the peptide (SEQ ID NO: 53), of the splenocyte derived from the above-mentioned mouse administered with a compound represented by the formula (17). Whether the helper peptide (SEQ ID NO: 102) works in the living body was determined by comparison of the numbers of IFNγ-producing cells obtained by re-stimulating the splenocytes derived from the mouse administered with the compound represented by the formula (17) and those derived from the mouse administered with the compound represented by SEQ ID NO: 53 with the peptide (SEQ ID NO: 53).

By a method similar to that in Experimental Example 19, CTL induction test was performed.

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIG. 14. In FIG. 14, the vertical axis shows the number of cells that responded among the plated cells, and the horizontal axis shows the compound or peptide administered to the mouse. In FIG. 14, the black bar shows the result of culture of HLA-A0201 transgenic mouse-derived splenocytes while being pulsed with the peptide shown by SEQ ID NO: 53, and the white bar shows the results of culture without pulsing. That is, the difference in the values of the black bar and the white bar shows the number of peptide-specific CTLs, and that the administration of the peptide shown by SEQ ID NO: 53 or the compound represented by the formula (17) resulted in the induction of CTLs specific to the peptide shown by SEQ ID NO: 53 in vivo in the mouse. In FIG. 14, the value of the white bar is not detected. This means that the splenocytes of the HLA-A0201 transgenic mouse did not react at all in the absence of pulsing with the peptide of interest. As a result of this test, IFNγ production specific to the peptide shown by SEQ ID NO: 53 was detected in the HLA-A0201 transgenic mouse-derived splenocytes. Moreover, in FIG. 14, the number of IFNγ-producing cells specific to the peptide shown by SEQ ID NO: 53 induced by the administration of a compound represented by the formula (17) was higher than that induced by the administration of the peptide shown by SEQ ID NO: 53.

From the above, it was demonstrated that the compound represented by the formula (17) can induce CTLs specific to the peptide shown by SEQ ID NO: 53. Administration of the compound represented by the formula (17) induced more IFNγ producing cells specific to the peptide shown by SEQ ID NO: 53 than administration of the peptide shown by SEQ ID NO: 53. It was assumed that the induction of cells reactive with the helper peptide shown by SEQ ID NO: 102 produced from the compound represented by the formula (17) enhanced induction of CTLs specific to the peptide shown by SEQ ID NO: 53. Therefore, it was strongly suggested that the compound represented by the formula (17) undergoes cleavage of disulfide bond and appropriate trimming by ERAP-1 in mice in vivo and is indeed processed into the peptides shown by SEQ ID NOs: 53 and 102.

That is, it was demonstrated that the compound represented by the formula (17), which is one embodiment of the compound of the present invention, is a conjugate wherein two different peptides form a composite via the disulfide bond shown in the formula (1), and is a cancer antigen peptide conjugate vaccine that indeed can induce CTLs and helper peptide reactive cells in vivo.

Experimental Example 21 Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The compound represented by the formula (18) synthesized in Example 147 was evaluated for the CTL induction ability by an in vivo CTL induction test using an HLA-A0201 transgenic mouse. The compound represented by the formula (18):

wherein the bond between C and C is a disulfide bond, is, in particular, a compound of the aforementioned formula (1) wherein cancer antigen peptide A is KIFGSLAFL (SEQ ID NO: 53) and cancer antigen peptide C is AKFVAAWTLKAAA (SEQ ID NO: 101). KIFGSLAFL (SEQ ID NO: 53) is an HLA-A0201-restricted cancer antigen peptide, and AKFVAAWTLKAAA (SEQ ID NO: 101) is an HLA-DR-restricted universal cancer antigen peptide (i.e., helper peptide).

The HLA-A0201 transgenic mouse is as described in Experimental Examples 4 and 19.

Whether the administration of the compound represented by the formula (18) results in the induction of CTLs specific to the peptide of interest (SEQ ID NO: 53) was determined based on the measurement of IFNγ production by re-stimulation, with the peptide (SEQ ID NO: 53), of the splenocyte derived from the above-mentioned mouse administered with a compound represented by the formula (18). Whether the helper peptide (SEQ ID NO: 101) works in the living body was determined by comparison of the numbers of IFNγ-producing cells obtained by re-stimulating the splenocytes derived from the mouse administered with the compound represented by the formula (18) and those derived from the mouse administered with the compound shown by SEQ ID NO: 53 with the peptide (SEQ ID NO: 53).

By a method similar to that in Experimental Example 19, CTL induction test was performed.

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIG. 15. In FIG. 15, the vertical axis shows the number of cells that responded among the plated cells, and the horizontal axis shows the compound or peptide administered to the mouse. In FIG. 15, the black bar shows the result of culture of HLA-A0201 transgenic mouse-derived splenocytes while being pulsed with the peptide shown by SEQ ID NO: 53, and the white bar shows the result of culture without pulsing. That is, the difference in the values of the black bar and the white bar shows the number of peptide-specific CTLs, and that the administration of the peptide shown by SEQ ID NO: 53 or the compound represented by the formula (18) resulted in the induction of CTLs specific to the peptide shown by SEQ ID NO: 53 in vivo in the mouse. In FIG. 15, the value of the white bar is not detected. This means that the splenocytes of the HLA-A0201 transgenic mouse did not react at all in the absence of pulsing with the peptide of interest. As a result of this test, IFNγ production specific to the peptide shown by SEQ ID NO: 53 was detected in the HLA-A0201 transgenic mouse-derived splenocytes. Moreover, in FIG. 15, the number of IFNγ-producing cells specific to the peptide shown by SEQ ID NO: 53 induced by the administration of a compound represented by the formula (18) was higher than that induced by the administration of the peptide shown by SEQ ID NO: 53.

From the above, it was demonstrated that the compound represented by the formula (18) can induce CTLs specific to the peptide shown by SEQ ID NO: 53. Administration of the compound represented by the formula (18) induced more IFNγ producing cells specific to the peptide shown by SEQ ID NO: 53 than administration of the peptide shown by SEQ ID NO: 53. It was assumed that induction of cells reactive with the helper peptide shown by SEQ ID NO: 101 produced from the compound represented by the formula (18) enhanced induction of CTLs specific to the peptide shown by SEQ ID NO: 53. Therefore, it was strongly suggested that the compound represented by the formula (18) undergoes cleavage of disulfide bond and appropriate trimming by ERAP-1 in mice in vivo and is indeed processed into the peptides shown by SEQ ID NOs: 53 and 101.

That is, it was demonstrated that the compound represented by the formula (18), which is one embodiment of the compound of the present invention, is a conjugate wherein two different peptides form a composite via the disulfide bond shown in the formula (1), and is a cancer antigen peptide conjugate vaccine that indeed can induce CTLs and helper peptide reactive cells in vivo.

Experimental Example 22

Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The compound represented by the formula (15) synthesized in Example 111 was evaluated for the CTL induction ability by an in vivo CTL induction test using HLA-A0201 transgenic mouse. The compound represented by the formula (15):

wherein the bond between C and C is a disulfide bond, is, in particular, a compound of the aforementioned formula (1) wherein cancer antigen peptide A is KIFGSLAFL (SEQ ID NO: 53) and cancer antigen peptide B is AKFVAAWTLKAAA (SEQ ID NO: 101). KIFGSLAFL (SEQ ID NO: 53) is an HLA-A0201-restricted cancer antigen peptide, and AKFVAAWTLKAAA (SEQ ID NO: 101) is an HLA-DR-restricted universal cancer antigen peptide (i.e., helper peptide).

The HLA-A0201 transgenic mouse is as described in Experimental Examples 4 and 19.

Whether the administration of the compound represented by the formula (15) results in the induction of CTLs specific to the peptide of interest (SEQ ID NO: 53) was determined based on the measurement of IFNγ production by re-stimulation, with the peptide (SEQ ID NO: 53), of the splenocytes derived from the above-mentioned mouse administered with a compound represented by the formula (15). Whether the helper peptide (SEQ ID NO: 101) works in the living body was determined by comparison of the numbers of IFNγ-producing cells obtained by re-stimulating the splenocytes derived from the mouse administered with the compound represented by the formula (15) and those derived from the mouse administered with the compound shown by SEQ ID NO: 53 with the peptide (SEQ ID NO: 53).

By a method similar to that in Experimental Example 19, CTL induction test was performed.

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIG. 16. In FIG. 16, the vertical axis shows the number of cells that responded among the plated cells, and the horizontal axis shows the compound or peptide administered to the mouse. In FIG. 16, the black bar shows the result of culture of HLA-A0201 transgenic mouse-derived splenocytes while being pulsed with the peptide shown by SEQ ID NO: 53, and the white bar shows the result of culture without pulsing. That is, the difference in the values of the black bar and the white bar shows the number of peptide-specific CTLs, and that the administration of the peptide shown by SEQ ID NO: 53 or the compound represented by the formula (15) resulted in the induction of CTLs specific to the peptide shown by SEQ ID NO: 53 in vivo in the mouse. In FIG. 16, the value of the white bar is not detected. This means that the splenocytes of the HLA-A0201 transgenic mouse did not react at all in the absence of pulsing with the peptide of interest. As a result of this test, IFNγ production specific to the peptide shown by SEQ ID NO: 53 was detected in the HLA-A0201 transgenic mouse-derived splenocytes. Meanwhile, in FIG. 16, the number of IFNγ-producing cells specific to the peptide shown by SEQ ID NO: 53 induced by the administration of the compound represented by the formula (15) was comparable to that induced by the administration of the peptide shown by SEQ ID NO: 53.

The results of Experimental Example 21 and Experimental Example 22 suggest that, when AKFVAAWTLKAAA (SEQ ID NO: 101) is used as an MHC class II-restricted peptide, an embodiment of the invention using AKFVAAWTLKAAA (SEQ ID NO: 101) as a cancer antigen peptide C is more preferable than that using AKFVAAWTLKAAA (SEQ ID NO: 101) as a cancer antigen peptide B in the aforementioned formula (1).

Experimental Example 23

Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The CTL induction ability of the compound represented by the formula (19) synthesized in Example 149 was evaluated by an in vivo CTL induction test using an HLA-A0201 transgenic mouse. KIFGSLAFL (SEQ ID NO: 53) and GLYDGMEHL (SEQ ID NO: 19) contained in the compound represented by the formula (19):

wherein the bond between C and C is a disulfide bond, are HLA-A0201-restricted cancer antigen peptides, and aKFVAAWTLKAAa (SEQ ID NO: 102) is an HLA-DR-restricted universal cancer antigen peptide (i.e., helper peptide).

The HLA-A0201 transgenic mouse is as described in Experimental Examples 4 and 19.

Whether the administration of the compound represented by the formula (19) results in the induction of CTLs specific to the peptide of interest (SEQ ID NO: 19 or 53) was determined based on the measurement of IFNγ production by re-stimulation, with the peptide (SEQ ID NO: 19 or 53), of the splenocyte derived from the above-mentioned mouse administered with the compound represented by the formula (19). Whether the helper peptide (SEQ ID NO: 102) works in the living body was determined by comparison of the numbers of IFNγ-producing cells obtained by re-stimulating the splenocytes derived from the mouse administered with the compound represented by the formula (19) and those derived from the mouse administered with the compound represented by the formula (4) with the peptide (SEQ ID NO: 19 or 53).

Specifically, the compound represented by the formula (4) was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 2 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 100 μg/site. In addition, the compound represented by the formula (19) was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 3.45 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 173 μg/site. The mole number of the compound represented by the formula (4) contained in the dosage amount of the compound represented by the formula (19) per mouse was controlled to be equal to the mole number contained in the dosage amount of the compound represented by the formula (4) per mouse. In addition, the concentration of DMSO contained in each emulsion was also set to the same level. One week later, the mouse was euthanized with CO₂ gas, the spleen was isolated, and splenocytes were prepared. IFNγ ELISPOT assay kit was used for the measurement of IFNγ production. On the previous day of splenocyte preparation, an ELISPOT plate was treated with an anti-mouse IFNγ antibody, and blocked with RPMI1640 medium containing 10% FBS the next day. The prepared HLA-A0201 transgenic mouse-derived splenocytes were plated at 0.25×10⁶ cells/well, on the blocked ELISPOT plate. Each of the peptides (SEQ ID NOs: 19 and 53) was dissolved in DMSO at 40 mg/mL, and further diluted with RPMI1640 medium containing 10% FBS to 40 g/mL. The diluted peptide (SEQ ID NO: 19 or 53) was added to the HLA-A0201 transgenic mouse-derived splenocytes at a final concentration of 10 μg/mL. The splenocytes added with the peptide were cultivated for 18 hr at 37° C., 5% CO₂, whereby peptide re-stimulation in vitro was performed. After the culture, the supernatant was removed, and the ELISPOT plate was allowed to develop color according to the attached protocol. The number of spots that developed color was measured by ImmunoSpot Analyzer (manufactured by C.T.L.).

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIG. 17 and FIG. 18. In each Figure, the vertical axis shows the number of cells that responded among the plated cells. In FIG. 17, the black bar and the white bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes in the presence and absence of the peptide of interest represented by SEQ ID NO: 19, respectively, and in FIG. 18, the black bar and the white bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes in the presence and absence of the peptide of interest represented by SEQ ID NO: 53, respectively. That is, the difference in the values of the black bar and the white bar shows the number of CTLs specific to the peptide of interest induced in the mouse in vivo by the administration of the compound represented by the formula (4) or formula (19).

In each Figure, the value of the white bar is not detected. This means that the splenocytes of respective transgenic mice did not react in the absence of the peptide of interest. As a result of this test, IFNγ production specific to the peptide of interest shown by SEQ ID NO: 19 or 53 was detected in the HLA-A0201 transgenic mouse-derived splenocytes administered with the compound represented by the formula (4) or formula (19). In each Figure, the number of the IFNγ-producing cells specific to the peptide shown by SEQ ID NO: 19 or 53 induced by the administration of the compound represented by the formula (19) was higher than that induced by the administration of the compound represented by the formula (4).

From the above, it was demonstrated that the compound represented by the formula (19) can induce CTLs specific to each of the peptides shown by SEQ ID NOs: 19 and 53. Administration of the compound represented by the formula (19) induced more IFNγ producing cells specific to the peptide shown by SEQ ID NOs: 19 or 53 than administration of the compound represented by the formula (4). It was assumed that induction of cells reactive with the helper peptide shown by SEQ ID NO: 102 produced from the compound represented by the formula (19) enhanced induction of CTLs specific to the peptide shown by SEQ ID NOs: 19 or 53. Accordingly, it was strongly suggested that the compound represented by the formula (19) undergoes cleavage of disulfide bond and appropriate trimming by ERAP-1 in mice in vivo and is indeed processed into the peptides shown by SEQ ID NOs: 19, 53 and 102.

That is, it was demonstrated that the compound represented by the formula (19), which is one embodiment of the compound of the present invention, is a conjugate wherein three different peptides form a composite via the disulfide bond, and is a cancer antigen peptide conjugate vaccine that indeed can induce CTLs and helper peptide reactive cells in vivo.

Comparative Example 1

Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The CTL induction abilities of the compound represented by the formula (4) synthesized in Example 29 and the peptides shown by SEQ ID NOs: 231 and 232 synthesized in Reference Examples 2 and 3 were evaluated by an in vivo CTL induction test using an HLA-A0201 transgenic mouse. The compound represented by the formula (4):

wherein the bond between C and C is a disulfide bond, is as described in Experimental Example 4. The peptides shown by SEQ ID NOs: 231 and 232 are long chain peptides wherein GLYDGMEHL (SEQ ID NO: 19), which is the HLA-A0201-restricted cancer antigen peptide A, and KIFGSLAFL (SEQ ID NO: 53), which is the cancer antigen peptide B, are linked by an amide bond.

The HLA-A0201 transgenic mouse is as described in Experimental Example 4.

Whether the administration of the compound represented by the formula (4) or the peptide shown by SEQ ID NO: 231 or 232 results in the induction of CTLs specific to the peptide of interest (SEQ ID NO: 19 or 53) was determined based on the measurement of IFNγ production by re-stimulation, with the peptide (SEQ ID NO: 19 or 53), of the splenocyte derived from the above-mentioned mouse administered with the compound represented by the formula (4) or the peptide shown by SEQ ID NO: 231 or 232.

Specifically, the compound represented by the formula (4) was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 10 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 250 μg/site. Also, the peptide shown by SEQ ID NO: 231 or 232 was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 9 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 225 μg/site. One week later, the mouse was euthanized with CO₂, gas, the spleen was isolated, and splenocytes were prepared. IFNγ ELISPOT assay kit was used for the measurement of IFNγ production. On the previous day of splenocyte preparation, an ELISPOT plate was treated with an anti-mouse IFNγ antibody, and blocked with RPMI1640 medium containing 10% FBS the next day. The prepared HLA-A0201 transgenic mouse-derived splenocytes were plated at 0.25×10⁶ cells/well on the blocked ELISPOT plate. Each of the peptides (SEQ ID NOs: 19 and 53) was dissolved in DMSO at 40 mg/mL, and further diluted with RPMI1640 medium containing 10% FBS to 40 μg/mL. The diluted peptide (SEQ ID NO: 19 or 53) was added to the HLA-A0201 transgenic mouse-derived splenocytes at a final concentration of 10 μg/mL. The splenocytes added with the peptide were cultured for 18 hr at 37° C., 5% CO₂, whereby peptide re-stimulation in vitro was performed. After the culture, the supernatant was removed, and the ELISPOT plate was allowed to develop color according to the attached protocol. The number of spots that developed color was measured by ImmunoSpot Analyzer (manufactured by C.T.L.).

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIGS. 19 and 20. In each Figure, the vertical axis shows the number of cells that responded among the plated cells. In FIG. 19, the black bar and the white bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes in the presence and absence of the peptide of interest represented by SEQ ID NO: 19, respectively, and in FIG. 20, the black bar and the white bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes in the presence and absence of the peptide of interest represented by SEQ ID NO: 53, respectively. That is, the difference in the values of the black bar and the white bar show the number of CTLs specific to the peptide of interest induced in the mouse in vivo by the administration of the compound represented by the formula (4) or the peptide shown by SEQ ID NO: 231 or 232.

In each Figure, the value of the white bar is not detected. This means that the splenocytes of respective transgenic mice did not react at all in the absence of the peptide of interest. As a result of this test, IFNγ production specific to the peptide of interest shown by SEQ ID NO: 19 or 53 was detected in the splenocytes derived from the HLA-A0201 transgenic mouse administered with the compound represented by the formula (4). On the other hand, while IFNγ production specific to the peptide of interest shown by SEQ ID NO: 19 was detected in the splenocytes derived from the mouse administered with the peptide shown by SEQ ID NO: 231, the number of cells that responded was small compared to that in the splenocytes derived from mouse administered with the compound represented by the formula (4). IFNγ production specific to the peptide of interest shown by SEQ ID NO: 19 was detected in the splenocytes derived from the mouse administered with the peptide shown by SEQ ID NO: 232. Further, while IFNγ production specific to the peptide of interest shown by SEQ ID NO: 53 was detected in the splenocytes derived from the mouse administered with the peptide shown by SEQ ID NO: 231 or 232, the number of cells that responded was very small compared to that in the splenocytes derived from the mouse administered with the compound represented by the formula (4)

Therefrom, it was demonstrated that the compound represented by the formula (4) of the present invention can efficiently induce both of CTLs specific to the peptide shown by SEQ ID NO: 19 and those specific to the peptide shown by SEQ ID NO: 53. On the other hand, the long chain peptides shown by SEQ ID NOs: 231 and 232 could not efficiently induce both of the CTLs.

Comparative Example 2

Evaluation of In Vivo CTL Induction Ability Using HLA-A0201 Transgenic Mouse

The CTL induction abilities of the compound represented by the formula (4) synthesized in Example 29 and the peptides shown by SEQ ID NOs: 233 and 234 synthesized in Reference Examples 4 and 5 were evaluated by an in vivo CTL induction test using an HLA-A0201 transgenic mouse. The compound represented by the formula (4):

wherein the bond between C and C is a disulfide bond, is as described in Experimental Example 4. The peptide shown by SEQ ID NO: 233 or 234 is a long chain peptide wherein GLYDGMEHL (SEQ ID NO: 19), which is the HLA-A0201-restricted cancer antigen peptide A, and KIFGSLAFL (SEQ ID NO: 53), which is the cancer antigen peptide B, are linked by an amide bond via 6 glycines as a peptide spacer.

The HLA-A0201 transgenic mouse is as described in Experimental Example 4.

Whether the administration of the compound represented by the formula (4) or the peptide shown by SEQ ID NO: 233 or 234 results in the induction of CTLs specific to the peptide of interest (SEQ ID NO: 19 or 53) was determined based on the measurement of IFNγ production by re-stimulation, with the peptide (SEQ ID NO: 19 or 53), of the splenocyte derived from the above-mentioned mouse administered with the compound represented by the formula (4) or the peptide shown by SEQ ID NO: 233 or 234.

Specifically, the compound represented by the formula (4) was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 10 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 250 μg/site. Also, the peptide shown in SEQ ID NOs: 233 or 234 was dissolved in dimethyl sulfoxide (DMSO) at 80 mg/mL, further diluted with water for injection to 10.5 mg/mL, and emulsified by mixing with an equal amount of incomplete Freund's adjuvant (IFA). The emulsified compound was intradermally administered to 2 sites at the base of tail of the mouse at 265 μg/site. Subsequently, similar processes to those in Comparative Example 1 were performed.

The results of IFNγ ELISPOT assay using the HLA-A0201 transgenic mouse are shown in FIGS. 21 and 22. In each Figure, the vertical axis shows the number of cells that responded among the plated cells. In FIG. 21, the black bar and the white bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes in the presence and absence of the peptide of interest represented by SEQ ID NO: 19, respectively, and in FIG. 22, the black bar and the white bar show the results of culture of HLA-A0201 transgenic mouse-derived splenocytes in the presence and absence of the peptide of interest represented by SEQ ID NO: 53, respectively. That is, the difference in the values of the black bar and the white bar shows the number of CTLs specific to the peptide of interest induced in the mouse in vivo by the administration of the compound represented by the formula (4) or the peptide shown by SEQ ID NO: 233 or 234.

In each Figure, the value of the white bar is not detected. This means that the splenocytes of respective transgenic mice did not react at all in the absence of the peptide of interest. As a result of this test, IFNγ production specific to the peptide of interest shown by SEQ ID NOs: 19 or 53 was detected in the splenocytes derived from HLA-A0201 transgenic mouse administered with the compound represented by the formula (4). IFNγ production specific to the peptide of interest shown by SEQ ID NO: 19 was detected in the splenocytes derived from the mouse administered with the peptide shown by SEQ ID NO: 233 or 234. However, while IFNγ production specific to the peptide of interest shown by SEQ ID NO: 53 was detected in the splenocytes derived from the mouse administered with the peptide shown by SEQ ID NO: 233 or 234, the number of cells that responded was very small compared to that in the splenocytes derived from the mouse administered with the compound represented by the formula (4)

Therefrom, it was demonstrated that the compound represented by the formula (4) of the present invention can efficiently induce both CTLs specific to the peptide shown by SEQ ID NO: 19 and those specific to the peptide shown by SEQ ID NO: 53. On the other hand, the long chain peptides shown by SEQ ID NOs: 233 and 234 could not efficiently induce both of the CTLs.

An example of a vaccine containing two antigen peptides is a cocktail vaccine containing the two different peptides in a single preparation. When a cocktail vaccine is produced, physical properties of cancer antigen peptides to be mixed would become one problem. As shown in Table 35 and Table 42, production of a cocktail of two antigen peptides requires processing of two peptides having different solubilities, namely, different physical properties, into one preparation. In contrast, the conjugate of the present invention is a compound wherein two antigen peptides are bonded via a disulfide bond, and shows a single solubility, namely, a single physical property. This means that the conjugate of the present invention has a single physical property and also responds to the two antigen peptides as shown in Experimental Example 4. In this regard, it has been shown that the conjugate of the present invention is a compound capable of inducing responses to the two antigen peptides without the need to consider factors such as interaction between the two antigen peptides, unlike cocktail vaccines.

Reference Example 10

By a method similar to that in Example 1, peptides consisting of the amino acid sequences of SEQ ID NOs: 239-242 were synthesized. Table 57 shows the result of mass spectrometry of each synthesized peptide.

The compounds of SEQ ID NOs: 239-242 were not the compounds of the present invention and were therefore described as Reference Examples.

TABLE 57 mass mass Ref. SEQ spectrometry: spec- Ex. amino acid ID LC-ESI/ trometry: No. sequence NO: MS m/z Calculated 10 KIFGSLAFLaKFVA 239 466.2 466.0 AWTLKAAa [M + 5H]⁵⁺ 11 KIFGSLAFLGGGGG 240 667.8 667.8 GaKFVAAWTLKAAa [M + 4H]⁴⁺ 12 aKFVAAWTLKAAaK 241 775.7 776.0 IFGSLAFL [M + 3H]³⁺ 13 aKFVAAWTLKAAaG 242 667.5 667.8 GGGGGKIFGSLAFL [M + 4H]⁴⁺

The peptides represented by SEQ ID NOs: 241 and 242 shown in Table 57 were synthesized by referring to the non-patent document, Cancer Science January 2012, Vol. 103, no. 1, 150-153.

Experimental Example 24

Evaluation of In Vivo CTL Induction Ability Using HLA-A2401 Transgenic Mouse after Filter Filtration

A homodimer of SEQ ID NO: 4 formed via a disulfide bond and the compound represented by the formula (5) are dissolved in water for injection at 3-10 mg/mL. The pharmacological activity of each compound is evaluated using an HLA-A2402 transgenic mouse (C57BL/6CrHLA-A2402/K) with the CTL induction activity as an index. For administration to the HLA-A2402 transgenic mouse, the compound is dissolved in water for injection, sterilized by filtration using a low protein-binding filter (a membrane filter of the grade aiming at sterilization for injection) and mixed with incomplete Freund's adjuvant to give an emulsion.

The emulsified compound is intradermally administered to the base of tail of the HLA-A2402 transgenic mouse. One week later, the mouse is euthanized with CO₂ gas, the spleen or inguinal lymph node is isolated, and splenocytes or lymph node cells are prepared. IFNγ ELISPOT assay kit is used for the measurement of IFNγ production. On the previous day of cell preparation, an ELISPOT plate is treated with an anti-mouse IFNγ antibody, and blocked with RPMI1640 medium containing 10% FBS the next day. The prepared cells derived from the mouse are plated on the blocked ELISPOT plate. A peptide (SEQ ID NO: 4) is dissolved in DMSO at 40 mg/mL, and further diluted with RPMI1640 medium containing 10% FBS to 40 μg/mL. The diluted peptide (SEQ ID NO: 4) is added to the HLA-A2402 transgenic mouse-derived splenocytes or lymph node cells at a final concentration of 10 μg/mL. The cells added with the peptide are cultivated for 16-20 hr at 37° C., 5% CO₂, whereby peptide re-stimulation in vitro is performed. After the culture, the supernatant is removed, and the ELISPOT plate is allowed to develop color according to the attached protocol. The number of spots that developed color is measured by ImmunoSpot Analyzer (manufactured by C.T.L.).

INDUSTRIAL APPLICABILITY

The compound of the present invention is useful as an active ingredient of a cancer vaccine that efficiently induces CTLs and is easy to produce. The present application is based on the patent application No. 2013-074441 (filing date: Mar. 29, 2013) and the patent application No. 2013-158386 (filing date: Jul. 31, 2013) filed in Japan, and the whole contents of the patent applications are herein incorporated. 

1. A compound represented by formula (1):

or a pharmaceutically acceptable salt thereof, wherein X^(a) and Y^(a) are each independently a single bond or a divalent peptide group consisting of 1-4 amino acid residues, and a total of the amino acid residue number for X^(a) and the amino acid residue number for Y^(a) is an integer of 0-4, cancer antigen peptide A is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues, an amino group of an N-terminal amino acid of the cancer antigen peptide A binds to Y^(a) in the formula (1), and a carbonyl group of a C-terminal amino acid of the cancer antigen peptide A binds to a hydroxyl group in the formula (i), and R¹ is a hydrogen atom; a group represented by formula (3):

wherein X^(c) and Y^(c) are each independently a single bond or a divalent peptide group consisting of 1-4 amino acid residues, and a total of the amino acid residue number for X^(c) and the amino acid residue number for Y^(c) is an integer of 0-4, cancer antigen peptide C is an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues, a carbonyl group of a C-terminal amino acid of the cancer antigen peptide C binds to X^(c) in the formula (3), and an amino group of an N-terminal amino acid of the cancer antigen peptide C binds to a hydrogen atom in the formula (3), and a thioether group in the formula (3) binds to a thioether group in the formula (1); or cancer antigen peptide D, wherein the cancer antigen peptide D is an MHC class I-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue or an MHC class II-restricted cancer antigen peptide consisting of 7-30 amino acid residues containing one cysteine residue, and a thioether group of the cysteine residue of the cancer antigen peptide D binds to a thioether group in the formula (1), provided when R¹ is a hydrogen atom, the sequence of the formula (1) is not identical to the partial sequence of a cancer antigen protein.
 2. The compound of claim 1, wherein X^(a) is a single bond, and Y^(a) is a single bond, an alanine residue, a leucine residue or a methionine residue, or a pharmaceutically acceptable salt thereof.
 3. The compound of claim 1, wherein X^(a) is a single bond, an alanine residue, a glycine residue, a serine residue or a tyrosine residue, and Y^(a) is a single bond, or a pharmaceutically acceptable salt thereof.
 4. The compound of claim 1, wherein X^(a) and Y^(a) are each a single bond, or a pharmaceutically acceptable salt thereof.
 5. The compound of claim 1, wherein the cancer antigen peptide A is a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 1-85, 87 and 88, the cancer antigen peptide C is a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 101 and 102, the cancer antigen peptide D is a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 3, 26, 37, 39, 56, 69, 70, 72, 75, 83, 84, 87 and 88, or a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 103, 104, 105, 106 and 107, or a pharmaceutically acceptable salt thereof.
 6. The compound of claim 1, wherein the cancer antigen peptide A is a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 3, 11, 13, 19, 26, 27, 29, 33, 40, 41, 43, 50, 53, 66, 83, 84, 85, 87 and 88, or a pharmaceutically acceptable salt thereof.
 7. The compound of claim 1, wherein the cancer antigen peptide A is a peptide consisting of an amino acid sequence selected from the following amino acid sequences: (SEQ ID NO: 19) GLYDGMEHL, (SEQ ID NO: 43) VLQELNVTV and (SEQ ID NO: 53) KIFGSLAFL,

or a pharmaceutically acceptable salt thereof.
 8. The compound of claim 1, wherein R¹ is a hydrogen atom, or a pharmaceutically acceptable salt thereof.
 9. The compound of claim 1, wherein the compound is a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 108, 111, 112, 114, 115, 116, 117, 119, 120, 121, 122 and 123, or a pharmaceutically acceptable salt thereof.
 10. The compound of claim 1, wherein R¹ is a group represented by the formula (3), or a pharmaceutically acceptable salt thereof.
 11. The compound of claim 1, wherein X^(c) and Y^(c) are each a single bond, or a pharmaceutically acceptable salt thereof.
 12. The compound of claim 1, wherein the cancer antigen peptide C is a peptide consisting of an amino acid sequence selected from the following amino acid sequences: (SEQ ID NO: 101) AKFVAAWTLKAAA and (SEQ ID NO: 102) aKFVAAWTLKAAa,

or a pharmaceutically acceptable salt thereof.
 13. The compound of claim 1, wherein R¹ is cancer antigen peptide D, or a pharmaceutically acceptable salt thereof.
 14. The compound of claim 1, wherein the cancer antigen peptide D is a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 3, 26, 37, 39, 56, 69, 70, 72, 75, 83, 84, 87 and 88, or a peptide consisting of an amino acid sequence selected from SEQ ID NOs: 103, 104, 105, 106 and 107, or a pharmaceutically acceptable salt thereof.
 15. The compound of claim 1, wherein the cancer antigen peptide D is a peptide consisting of an amino acid sequence selected from the following amino acid sequences: (SEQ ID NO: 87) VYGFVRACL and (SEQ ID NO: 88) SLLMWITQC,

or a pharmaceutically acceptable salt thereof.
 16. The compound of claim 1, wherein the cancer antigen peptide D is a peptide consisting of the following amino acid sequence: (SEQ ID NO: 103) aK-Cha-VAAWTLKAAa-Ahx-C,

or a pharmaceutically acceptable salt thereof.
 17. The compound of claim 1, wherein the cancer antigen peptide D is a peptide consisting of an amino acid sequence selected from the following amino acid sequences: (SEQ ID NO: 104) AADHRQLQLSISSCLQQL, (SEQ ID NO: 105) RNGYRALMDKSLHVGTQCALTRR, (SEQ ID NO: 106) KKLQCVQLHVISM and (SEQ ID NO: 107) GSYVSRLLGICL,

or a pharmaceutically acceptable salt thereof.
 18. A pharmaceutical composition, comprising: the compound of claim 1 or a pharmaceutically acceptable salt thereof; and a pharmaceutically acceptable carrier.
 19. A method of treating or preventing cancer, comprising administering a therapeutically or prophylactically effective amount of the compound of claim 1 or a pharmaceutically acceptable salt thereof to a cancer patient positive for a cancer antigen protein in need thereof. 